[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 happy to exchange your [OLD PRODUCT, ex. Magnaflux compressor, model 452B] (invoice #[INVOICE NUMBER]) with [NEW PRODUCT, ex. model 542X].  [STATE HOW DIFFERENCE IN PRICE WILL BE HANDLED, ex. Since the 542X is priced $987.62 less than the 452B, I have credited your account in that amount.]

Since your satisfaction is our goal, do not hesitate to call me at XXX-XXXX if I can be of any further assisstance.

Sincerely,

[YOUR NAME, ex. Jill Jones]