Ebay-Paypal sale question?

I thought I'd go here.

I had sold my laptop on ebay, the buyer gave me his address and name. Everything's fine until here. Then he transferred the money to PayPal. But there was a completely different address and name. I made the buyer aware of this and paid the money back. Thereupon the buyer thinks to change his address (which he did to the one that was sent on Ebay) but his name was still different.

Then I sent the money back a second time, with the answer that this time the name is wrong and that it doesn't work. May I block the buyer now?

May I block the buyer now?

No.

You have a legally binding sales contract and have to send the laptop to the address on file with PayPal, which the buyer can change as often as he wants.

Yes, but the name wasn't the one with the address, the package wouldn't have arrived at all, I paid the money back.

What are you talking about

He gave the money back, i.e. There's no sale.

And if he constantly changes his address + name that is his problem and not the problem of the seller. This is still a fraud what the buyer wants to deduct.

Thank you very much @ SIR420743