How to Write an Effective Complaint Letter

03 Nov 2026

A complaint letter works best when the reader can understand the problem in one minute and knows exactly what you expect.

Include these details

• Your reference: consumer number, account number (last 4 digits only), order number or earlier complaint number.
• The date and place of the problem.
• A factual description — what happened, how long it has continued and how it affects you.
• What you have already done (earlier calls, visits, complaint numbers).
• The remedy you want: correction, refund, repair or an explanation.
• A reasonable deadline, for example 15 days.

Keep proof

Attach copies, never originals, of bills, photographs, screenshots and messages. Ask for a written acknowledgement or complaint number. If you send by post, use registered post or speed post and keep the receipt.

If there is no reply

Send a polite reminder quoting your first letter. Then use the next level: a senior officer, the department’s online grievance portal, the ombudsman for banking matters, or the consumer commission for consumer disputes. In an emergency or a crime in progress, call 112 instead of writing a letter.

Our complaint letter formats follow this approach.