Your payment of $[amount] pursuant to our invoice dated __________, 200_ has not arrived by the date required. We are sure that this is an oversight and ask that you please send it today in the enclosed self-addressed envelope. If we are forced to spend time collecting overdue accounts receivable, we will not be able to offer our valued clients, such as yourselves, our current prices.
If you have already sent your payment to us, please accept our thanks. If you have any questions, please feel free to call the undersigned at (____)__________.