It cannot be that hard, can it?

I am really losing my patience now. We purchased a bed of poor quality and returned it and agreed to credit. First of all when they collected it I was not issued with a copy of the collection that I signed off, so I took a picture of the document that I signed. After 21 emails I still have not received my credit voucher. Apparently they sent it in a separate email which I did not receive. I do not understand what the big issue is in sending it to me in a reply on the conversation I am busy with. The stupidity is killing me. Can someone please assist me with getting my credit back. This is now getting ridiculous.