Austin Parker
123, X Street, Y Avenue
Manhattan, NY-10009
(123) 456-7890
[Subject: Normally bold, summarizes the intention of the letter] -Optional-
Dear Austin Parker,
Please accept our sincere apologies for the mistake we made on our quotation for the renovation of your nursery. The amount that was indicated is not yet inclusive of the wallpaper and the carpet that you specifically chose. As you can see from the materials price list, there will be an additional $160 for both of the items mentioned earlier. Again, we are really sorry for the oversight.
Sincerely,
Similien