If a customer does a chargeback through their credit card company the ONLY way you will win is if the card was presented and swiped or imprinted. Almost ANY PayPal payment made with a credit card can be reversed, if the charge was made directly with you there is a chance you can provide enough evidence to the credit card company to win but even then it's rare.
Accepting credit cards via PayPal is always risky, the risk is directly related to the flakiness of your buyers which is directly related to the nature of the goods you sell. PayPal WILL NOT work on your behalf, why should they, it's far too easy for them to just grab the money back from you.
I sell collectable records and cd's, most of my buyers are serious collectors not scam artists so I have few problems but if you sell common items available from many sellers / sources it's a whole different "game".
Ben

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.