Asked for item to be canceled, haven't received Item or got my money back - eBay?

3 days ago my boyfriend had bought a pair of Dr Dre headphones from eBay, not knowing that I had already bought him a pair for his birthday, which I cannot take back. I emailed the seller to ask to cancel and the seller seemed fine about it and said it would be fine to cancel the order, although my boyfriend had already paid. 3 days later and he hasnt had the money back and the item hasnt been sent. What should he/I do?