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.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. We have identified the following overpayment and are in good faith voluntarily refunding all monies collected in error. The salary overpayment resulted because . In 1888, James Bryce wrote that sunlight kills the germs of corruption that can infect a government, and his words remain true today.