Well, you did the first step correctly. You contacted the seller and asked how he was going to make it right.
However, when that does not encourage the seller to take immediate action, eBay and Paypal have a Buyer Protection program in place.
You have 45 days from the transaction to start a claim with that program. The Customer Support button in the top right hand corner of this page is where to start.
But.
45 days.
Long gone.
If you used Paypal to process your credit card payment (or if you paid the seller directly by credit card) you might possibly have time to get a refund under the card's Chargeback program.
Act immediately, cards rarely will allow more than 120 days (and usually only 90) for complaints.
You will probably be required to prove return to the seller in order to get a refund. But time is not on your side.