[DATE, ex. Wednesday, June 11, 1998]
 

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

Dear [NAME, ex. John Smith], 

I was deeply embarrassed by your [STATE FORM OF COMMUNICATION, ex. telephone call yesterday].  Before apologizing, however, I want to assure you that I will not allow such an error to recur; our company has a favorable record of customer satisfaction and I will not allow that to change.

[STATE WHAT HAS OR WILL BE DONE, ex. Immediately following our conversation, I ordered our delivery trucks to arrive at your premises tomorrow to deliver the missing products and pick up the incorrectly-shipped items.]  I apologize for the inconveniences this must have caused you.  Please call me at XXX-XXXX if there is anything I can do for you. 

Sincerely,

[YOUR NAME, ex. Jill Jones]