Help getting my refund

[lapoll7]

I have a seller that I purchased an item from. I pay for my items usually as soon as I receive the notification that I have won. In this case, I paid for it about 2-3 hours after I won the bid. Then I opened my email to find that the seller had canceled the transaction claiming that she "was out of stock". In the cancelation, it said that I had not paid for the item so I didn't get to respond at all. So I notified the seller that I wanted a refund and she became very upset saying that she had okayed for me to get a refund so it was no longer her problem. So long story short, I opened a claim and the same thing is happening. I'm stuck in this vicious circle of "I told them to refund you. I can't do anything else". I can't choose the option of the case being resolved because I still don't have my money and she refuses to contact them and is laughing about the case just going in circles. What do I need to do to get my money back?