[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],

Thank you for your letter of [DATE, ex. June 10]; you are absolutely correct and we owe you an explanation for our error.

[GIVE EXPLANATION, ex. Indeed, your payment was received in a timely manner.  However, our data entry personnel made an error when keying the date of receipt.]  [STATE WHAT WILL HAPPEN TO ACCOUNT AND STATE NEW BALANCE, ex. Your account has been credited $52.20, leaving a balance of $1,023.43 due.]

Please accept my apologies.  We will take every effort to ensure that such error does not recur.

Sincerely,

[YOUR NAME, ex. Jill Jones]