DOB NOW filing fee screen. This brief but important letter notifies a customer that he or she has overpaid you.It can serve as a very good customer relations letter. Our document template is designed to make the process of writing an "Inform a Customer of an Overpayment" letter quick, easy, and stress-free. Call 311 or 212-NEW-YORK (212-639-9675) for help. Where feasible, if you are reporting more than one item for the same customer, one letter should address all the items you are reporting. Costs.