[Your letterhead, if desired; if not, your return address]
[Date of letter-month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
We are contacting you to remind you that payment of $275.67 on your account number 5321114 was due on 2/27/11, and we have not received your payment yet.
Please contact our Customer Service department immediately at (215) 555-1212 so that we can discuss options with you. You have the option to set up payment arrangements, such as a payment plan that allows you to pay the balance over time, so ask about this when you call.
If you have already sent your payment, please disregard this notice. Thank you for your prompt attention to this matter.
[Sender's first and last names]