ebay dispute problem question?

ok, so I sold an item which the buyer said was not as described, he actually asked me detail about the item in the messages section AFTER he paid. I agree that I did not describe the item to his liking so he opened a dispute against me. According to ebay (and most uk consumer) policy, the buyer is entitled to a refund once the item is returned, fine. I email the buyer, quite politely, saying return the item to me and I will refund. He then wants the original postage back plus his costs to send it back to me. I agree to the original costs but not for him to return it to me. Nothing. I email ebay saying I'm quite happy to refund but to date he's not returned my item so I can refund. Next thing I get an email from ebay saying the case is closed and they've refunded out of my account so now I have no money and no item. If you go to Asda or Tesco's do they refund my petrol money to return the item, no? Do they refund me and allow me to keep the item? No. There's very few mail-order companies out there that will refund return costs so why have ebay done this? What legal rights do I have as I am without (quite an expensive) item and my money...surely this isn't right? HELP!?