I am sorry you got a less than honest buyer but you can hardly blame ebay for you/your son not knowing how to handle the situation.

If a buyer opens a dispute in ebay for an item being Not As Described the the seller is responsible for the return postage.....that is ebay policy, and not just the buyer's whim.

Your buyer obviously knows the system and in this case used it correctly.....even if the buyer had not told your son to hit the return accepted button it would still have been forced by ebay.

In fact, if ebay is involved the buyer would probably received the refund AND kept the item.....you would have been out of pocket for the item and postage and had nothing to resell.

As it is now, you still have your phone and it has only cost you the return postage.