you went about this all wrong.. Now you have to go through this whole process. For future reference, your order of action should have been:
1) Apologize profusely for screwing up the seller's day.
2) Ask very nicely for a refund
3) if he gives you some bull**** line like restocking fees on an item that he couldn't have possibly shipped or isn't even in his possession yet, then you should politely tell him why you shouldn't be charged. Mention that there is no restocking fee on ebay and the above stuff about how restocking fees work.
4) wait at least 24-48 hours for a response
5) 95% of the time they will then issue a complete refund. For the other 5% of the time, it is now time to escalate with paypal and ebay and call your bank and etc.
If you follow these steps you will get your money back MUCH faster. If you just go effing rambo on claims you'll be locked into dispute for a drawn out period of time and neither party is really happy in the end. Kinda a lose-lose scenario whereas by doing the above in the correct order will most of the time end up in win win situation.
If he refunds give him a stale review mentioning his shoddy business practice of charging restocking fees on prerelease goods. (reviews are everything on ebay)
HAPPY BIRTHDAY!! You grow some, you learn some. CHEERS!