[Tenaxium]

Say the buyer agreed to the Terms of Service before buying, and the terms of service stated no chargebacks.

[Tastylicous]

I'd also tell them to check the IP-Address that was used to send the money and compare it to his earlier IPs.

[billy.]

Why did he sent it in different transactions? By any chance that all those transactions are from another PayPal account? If so, he obviously paid you with hacked PP accounts.

[❁Sakura❁]

You will loose
When doing an unauthorized transaction you loose the money no matter what. It means someone "hacked" the PayPal account. Showing how shitty their protection for a login is its piss off
This is why you don't use paypal. Maybe for withdrawalals. Use like btc then do a verified currency exchange

[illuminatiJake]

The thing is that -- what if you're talking to the PayPal account holder and not the original purchaser? What if the purchaser used a hacked PayPal account? There's an unknown.