Dear

In my letter of (date) , I explained that the merchandise
I ordered from you hadn't arrived. I am attaching a copy of
that correspondence for your convenience.

Having received neither the merchandise nor a response to my
previous letter, I am requesting that you refund the (amount)
remitted with my order. Attached is a copy of my cancelled
check.

I shall be looking forward to receiving my refund promptly.
Thank you for your immediate attention to this matter.