I remember back in a old guild in ffxi our leader got banned for POS hacking and stuff. A month later his brother got banned since he was on the same CC.Blizzard has Data bases of all customer info. I got banned in World of warcraft once upon a time, 1-2 years later I went and re-bought the game with the same Credit card from bnet. After about 30-45 min of playing, I got banned again for no reason. It took me 3 weeks to appeal the ban which got approved with a "we are sorry, our systems flagged your credit card".