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.IMPORTANT: If we told you in the overpayment notice that you are responsible for a family member's overpayment, complete Section 3. Otherwise, go to Section 4. Our document template is designed to make the process of writing an "Inform a Customer of an Overpayment" letter quick, easy, and stress-free. You have to tell your credit or debit card company about any error you're disputing within 60 days of when the first statement with the charge was sent to you. Fill out and submit this form. Call toll free: 1-800-743-8525 or for hearing or speech impaired use TDD 1-800-952-8349.