I no longer have access to old PC to deactivate Acrobat XI Pro serial number.

Yes, I understand it can be installed on two machines at one time.  However, now that I've reinstalled Adobe on my new machine, and I'm receiving the error message it has been activated on the maximum number of machines.  I'm trying to contact Adobe support, but each time I go through the support links I'm directed back to the forums.  I need some one from Adobe to reset my serial number.  Where is the phone number or link to chat support to do this?