I think paypal are saying that the fee is actually charged by the bank. If a chargeback is won I believe that the bank should pay this back, seems far to me. They are at fault.

I didn't realise that the fee was still charged even if a refund is made (withought fighting it). I have refunded a chargeback for an order I hadn't even packaged up. It is hard to see because on the paypal transaction page none of these fees are displayed until you dig a little deeper.