Returned goods & still no refund or feedback

I returned an item to Groupon that I bought. I have proof that they collected my item. I am still waiting after following up about my refund and after 2 emails from Groupon, they say they have not got a solution for me. It is simple, give me my refund!! I paid you R400 and I returned the goods, so where on earth is my money that you owe me??