If you funded your paypal payment with a credit card, you might be able to do a chargeback by calling the card company and asking them what you need to do.
You should have filed a not as described dispute. It doesn't matter how much the seller tries to delay the process, it's up to you to file within the time period regardless of what the seller may have said.
Of course the seller is not responding. They have your money and the item.
If it has been less than 60 days since end of sale, you can still leave feedback if you haven't done so already.
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Non payers should get unpaid item strikes and be added to block bidders lists. Period.