Gentlemen:

This is to acknowledge our receipt of your invoice #

A check of our records indicates that payment for this
invoice was made on (date) with our check #
payable to you in the amount of $

Please review your records and bank deposits to be sure
that you have not received our payment. If you are still
unable to find a record of payment, let me know, and I
will request a photocopy of our check, and forward it to
your office. This normally takes about 30 days.

If I do not hear from you, I will assume that you have
found our payment and have appropriately credited our
account.