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.