[DATE, ex. Monday, March 31, 2008]

[NAME, COMPANY AND ADDRESS, ex.
Link Building
XYZ Inc.
1234 First Street
Suite 567
Anycity, Anystate  85245]

Dear [NAME, ex. Link Building],

We have just received your payment of $[AMOUNT, ex. 5,200.24] for [PRODUCT(S) / SERVICE(S), ex. your order of five Magnaflux compressors].  Thank you for your payment.  Our records, however, indicate that the total billing for that invoice (#[INVOICE NUMBER]) is $[AMOUNT, ex. 5,400.24].  Please check your records to ensure that I have not made a mistake.  If you find that we are correct, please be so kind as to send the remainder, $[AMOUNT, ex. 200.00], at your earliest convenience.  Otherwise, please call me at XXX-XXXX so that we may update your account accordingly.

Sincerely,

[YOUR NAME, ex. Jill Jones]