[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],

I am in receipt of your invoice #[INVOICE NUMBER], dated [DATE, ex. June 8, 1998].

I believe there has been a slight mistake.  [STATE NATURE OF MISTAKE, CITING AND ENCLOSING SUPPORTING DOCUMENTS, ex. As per our order #23345 and shipment receipt (which I have enclosed for you), we ordered and received only five A465 compressors, as opposed to the six invoiced.]  Please check your records and inform me if I am incorrect.

I request that you send me an updated invoice at your earliest convenience so that we may process your payment.

Sincerely,

[YOUR NAME, ex. Jill Jones]