I’m able to reach them after I managed to wait for a few minutes on the phone, and all they can say is that they have to freeze my account without any possibility of refunding my balance. I asked them if they could mail me a cheque (following an advice given from a friend), but they refused my request.

Bummer, seems Paypal users has no way to protect themselves from these fraudulent buyers/payers.

Oh well, life goes on…