Write a formal complaint or admin letter
Refunds, disputed charges, repairs, unpaid invoices, appeals: what goes in each letter, the tone that works, and where AI is wrong about your rights.
The washing machine arrived on the 14th, it has flooded the kitchen twice since, and the shop has now told you three times that someone will call you back. You want to put the complaint in writing. What is needed is something with a date on it, because a letter leaves a record and a phone call leaves your word against theirs.
Most people write that letter badly, and being a bad writer has nothing to do with it. They write it while angry, or so carefully that the request ends up buried in paragraph four. Complaint letters work on specificity and on a clear ask. Nobody in a customer service queue has ever been moved by an adjective.
Working out what a letter you received means is a different job. This page starts once you know what you want.
Platform: Web, iOS, Android
AI models: 60 from 18 providers, 21 of them on the free plan
Free plan: 50 messages per 24 hours
Price: Free, or Pro at $20.99/mo
The four parts, and the one people leave out
Every letter below is these four things, in this order.
Who you are and what this is about. Account number, order number, policy number, address, the date of the thing that went wrong. Put them in a block at the top, not woven into a sentence.
What happened, in dates. Delivered on the 14th. Reported on the 16th. Told on the 21st that an engineer would call. No call.
What you want, exactly. A figure, a named action, and a date by which you want it.
What happens next if you do not get it. A flat statement of the step you intend to take.
Part three is the one that goes missing. People describe the problem in detail, sign off with "I hope you can resolve this", and hand the other side the pen. Make the reader work out what you want and they will decide in their own favour, or decide nothing.
Arrangement is the part AI is good at. Six letters follow, each with what to put in, the tone that gets an answer, and a verdict.
A refund the shop is not giving you
It arrived broken, and the shop is stalling.
What to include. Order number, purchase and delivery dates, the amount paid, what is wrong and when you noticed. Every contact you have already had, with dates and ticket references. Then one outcome: refund, replacement, or repair. Asking for all three reads as an opening offer.
The tone that works. Flat. The pressure comes from the record. Try: "Write a complaint to a retailer using only the facts below. Under 300 words. No adjectives about how I feel. Reference numbers in a block at the top, the outcome in its own paragraph. Do not cite any law."
Verdict. The strongest use here. The model arranges better than you do at half past ten at night.
The service that never happened
The photographer who did not turn up, the course cancelled after you paid.
What to include. What you booked against what was delivered. The amount paid and the date it left your account. Any knock-on cost you can evidence. Then the figure you want back, with the arithmetic shown.
The tone that works. Businesslike, with the sum spelled out. Ask for the calculation as short lines and a total. Vagueness about money invites a goodwill voucher instead.
Verdict. Worth it, on the condition that you supply the numbers. A model asked to estimate your loss will invent something plausible and useless.
Disputing a charge or a fee
A subscription that renewed after you cancelled.
What to include. The line as it appears on the statement, verbatim, with date and amount. When and how you cancelled, and any confirmation you got. Then the ask: reverse it, and confirm in writing that it will not recur.
The tone that works. Short, and say the word limit in the prompt. Six sentences is plenty; disputes get read by someone processing forty of them, and a model left alone will give you 600 words that nobody finishes.
Verdict. Good, provided you paste the statement line in exactly. Paraphrase it and the model smooths it into something that no longer matches their system.
Getting a landlord to fix something
The damp, the boiler, the window that never shuts.
What to include. Address and tenancy reference, what is broken, when it started, and every previous time you raised it, with the method: text on the 3rd, email on the 11th, spoke to the agent on the 19th. What the fault is doing to the property or to you. Then a specific request, an access window, and a date.
The tone that works. Cooperative and dated. You may need this person for another year, so it has to be firm without turning adversarial. Tell the model to leave out anything about your rights or your deposit; that is a different letter.
Verdict. Solid for the record it builds. Weak on anything turning on housing law, which varies between countries and often within them.
The invoice that is 40 days late
This one goes to a client rather than a colleague, and it is your money.
What to include. Invoice number, issue and due dates, amount outstanding, days overdue. The work it covers, in one line. Previous reminders, with dates. Then a payment date and a way to pay.
The tone that works. Neutral and slightly boring, the register that gets invoices paid. The trap runs both ways: too apologetic and it slides down the pile again, too sharp and you damage a paying relationship. Ban the stock phrases: "just following up" and "gentle reminder" are everywhere in the training data, and every recipient reads them as passive aggression. Try: "Five sentences. Overdue amount and days outstanding in the first line. One clear way to settle it. Do not apologise for chasing."
Verdict. Where a model earns its keep. Polite firmness is hard to hit yourself when you are 40 days out of pocket.
Appealing a decision that went against you
A refused claim, a rejected application, a penalty notice.
What to include. The reference of the decision and its date. The stated reason, quoted word for word. Then what you are contesting: a fact they got wrong, or evidence they did not have. List nothing you cannot back up.
The tone that works. Narrow. Appeals are lost by arguing everything at once. Give the model the quoted reason and your strongest point, and tell it to answer that reason directly and stop. With more than one point, ask for them numbered, strongest first.
Verdict. Use it for structure. Never let it decide your grounds or tell you whether you have a case.
Where it will let you down, confidently
Everything above is arrangement and register. Rights are another matter.
Ask for a complaint letter and many models reach for a legal hook unprompted: a named statute, a cooling-off window, a refund period stated as fact. Some will be accurate. Some will be law from a country you do not live in, delivered in the same confident sentence. Our own company is Belgian, most of our readers are in Europe, and consumer rules here differ by country and sometimes by region.
A letter citing a rule you have not checked is worse than one citing nothing. The other side has to correct you once, and the exchange stops being about the washing machine.
Two habits fix this.
Tell it not to cite anything. "Do not reference any law, regulation or statutory right" belongs in the prompt by default. A clear account of what happened and what you want is a complete letter without one.
If it cites anyway, make it show its working. Ask: "Name every rule you relied on, the country it applies in, and what I would need to check to confirm it applies to me." Then check it, or cut it. Never send a citation you have not verified.
Apply the same discipline to the facts. Ask it to list every date, amount and reference number it used, and read that list against your paperwork. Thirty seconds, and it catches transposed digits.
For the rights question itself, ask someone whose job it is. Bought from a business in another EU country, Norway or Iceland? The European Consumer Centres Network gives free advice through 29 centres in 24 languages. For a purchase at home, your national consumer authority or the sector ombudsman is the right door. MultiChats does not give legal advice, and neither does this page.
Before you paste your account number in
These letters carry identifiers: bank references, addresses, policy numbers. MultiChats does not train on your conversations. What the provider behind a given model does varies, and six of the 60 say so on their info card. Grok's says it plainly: "xAI may use your conversations to train Grok models." The other 54 say nothing, so strip any digit the letter does not need.
Two versions, then pick one
The same complaint wants a different register at each stage. Ask for both at once: "Give me two versions. One polite, assuming a mistake. One formal, assuming I have been ignored." Send the polite one. Keep the formal one for the reply that never comes.
For a second opinion, branch the answer and pick another model. The action is Try Again on the web and Branch here in the mobile app, and the labels are a trap: on a phone, Try again is regenerate, which deletes the draft it replaces. Branching leaves the first draft alone and opens a new thread. Two models given identical facts open with different sentences, and the opening line carries most of the tone.
Frequently asked questions
Can I write these on the free plan?
Yes. 21 of the 60 models are free, and 50 messages per 24 hours is more letters than most people write in a year.
Will the model know my consumer rights?
Treat every rights claim as unverified, whichever country you are in. Write the letter without citations, and get the rights answer from a consumer body or a qualified adviser.
Should the letter mention legal action?
Only if you mean it and know what the next step is where you live. An empty threat is easy to spot.
Can it check a rule for me?
Web search runs inside the conversation and returns links. Free accounts get 2 searches per 30 days, and on mobile search sits behind Pro at the button. Open the link and read it yourself: a search result is where the check starts.
Free to start, Pro at $20.99/mo. Start a chat and write the first one.