That's weird. Once you notify them that it's no longer in your possession then they have an obligation to deactivate it and remove it from your account. At the very least they must deactivate it so there's no way you should be on the hook for any ppv charges. If they use it for illegal purposes it doesn't effect you either but make sure you notify them that you have sold it.
If they're giving you the runaround you should speak to the business office and make it clear that you have done your part and notified them of the transfer.