Dear ____ (name): We are in receipt of your letter regarding the merchandise purchased _____ (time) and then returned. You noted in your letter that one of our store associates had made a mistake and you received the incorrect package. As you can imagine, we deal in a high volume of sales. Therefore, occasional errors such as the one you experienced do occur. However, we are proud of the fact that these errors are few and far between in number. We are enclosing a check for the full amount of your purchase. Your patronage is highly valued. Please drop in again and let us see that your next purchase is handled correctly. Sincerely, (Name) (Title)