Jack Martinez
456, X Street, Y Avenue,
Fillmore, UT-84631
Cell:-(123) 456-7890
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Jack Martinez,
We are thankful to you for having pointed out the mistake in the sales invoice. It seems like the typist had actually replaced the numbers. I am correcting the mistake and also arranging for a new invoice to be sent to you. You should not worry about making the payments until your new and corrected invoice comes to you. Thanks for your understanding.
Sincerely,
Eako