Also most Game's don't look kindly on buying accounts, so support is out of the question... The most you can do is what SuperSkunk said and change all address details, secret question/answer etc immedeatley...
Another option would be to have the current owner of the account set up a new email, and use it for the password reset email to be left in there. And to give you the password to this email account. Try buying from a reputable site, or one that has a rating system implemented and the seller has ++ rating and not just ++ from 1 or 2 friends of his ^__^