View the list of Sample Business Letters Apology to Customer for Accounting Error Disclaimer: Be aware that some of these sample letters have legal, financial, or other implications. If you are not sure about the use of any letter, consult with an appropriate professional first. Apology to Customer for Accounting Error Dear Thank you for your recent correspondence regarding your account number ____________. We were able to track down the error and have credited your account accordingly. A report to this effect has also been sent to our credit reporting company. As of this date, your account balance is $_____________. You are a valued customer and we apologize for any inconvenience this mix-up may have caused. If we may be of further assistance please contact this office at your convenience.