If someone get's their cd-key stolen or keygenned, there's nothing PBB nor EB can do about it...
Unbanning isn't an option, since together with the innocent person, also the cheaters using the key will be unleashed.
For example for CoD 4 there are very many such scams... Some disguise themselves as hacks, some call themselves lvl-55-cheats or whatever else comes to mind. And many SoF2 copys are being sold with keys, that were generated with keygens and banned.