You need to tell the creditor that there is a billing error on your statement. Tell them what the mistake is, the amount that is wrong, and the date of the charge you question. If you need more information about a charge, ask for any proof the creditor has that you made the purchase. You must include your name, address and account number in your letter. You should also send copies (not originals) of any receipts, sales slips or other documents that support your claim. It is a good idea to send the letter by certified mail and to get a receipt to prove the creditor got your complaint. You should also date your letter and keep a copy for your own records.