[NAME, COMPANY AND ADDRESS]
I am in receipt of your invoice #[INVOICE NUMBER], dated [DATE].
[STATE WHAT YOU HAVE AND HAVE NOT RECEIVED, ex. Although the shipment of 20 compressors has arrived, we have not yet received the 2 1/2" piping required to install them.] I will be pleased to send you a check in the amount of $[AMOUNT] once we receive the above item{s} and the order is complete.
Sincerely,
