SAMPLE - APOLOGY FOR INCORRECT PAYMENT: OVERPAYMENT

[NAME, COMPANY AND ADDRESS]

A check of our records has revealed that we have made an incorrect payment to you in settlement of your invoice #[INVOICE NUMBER].  Our check #[CHECK NUMBER] for $[AMOUNT] is $[AMOUNT] in overpayment of the total amount due, $[AMOUNT].

[MENTION HOW YOU REQUEST THE OVERPAYMENT TO BE HANDLED, ex. As the overpayment is not insignificant, I would greatly appreciate the difference of $1,000 to be sent to us.]  I thank you for your consideration and look forward to continued business together.

Sincerely,