The seller scammed you. When he persuaded you to close the dispute, you lost all chance of being refunded through eBay/Paypal.
If you had left the case open, either he would have refunded you through the case, and got his selling fees back and no black mark on his selling record, or PP would have refunded you from their pocket and gone after him for the money. He would also get that black mark.
No case, no reason to refund. PP/eBay assumes you are satisfied when you close the case.
It's very late but....
If you use Paypal to pay from your credit card, call the customer service number for the card and ask about a chargeback. They have deadlines so do this immediately.
You have up to 60 days to leave feedback. The most effective feedback is calm and factual. At the same time you will be asked to leave Detailed Seller Ratings. A normal transaction get Five Stars. The lowest rating is ONE Star. No stars is a freepass. A seller whose DSRs drop below 4.3 finds his ability to list and sell on eBay severely restricted.
You can leave a Response to any feedback indefinitely. Yours or the Seller's. The most effective Responses are calm and factual.
I hope this learning experience did not cost you a lot of money.
