Acrobat XI Pro perpetual licence – activation limit reached, old computer unavailable

I own a legitimate perpetual Adobe Acrobat XI Pro licence.
I am moving the licence to a replacement computer because one of the previously activated computers is no longer available.
Acrobat XI’s built-in offline activation process still works. Adobe’s official offline activation website recognises my serial number, but returns:
“Activation limit reached for Acrobat XI Pro. This Serial Number has already been activated on 2 machines. Please deactivate one of the other computers and try again.”
I cannot deactivate one of those old machines because I no longer have access to it. I have also tried Adobe Customer Care chat, but it will not connect me to an advisor because Acrobat XI is discontinued.
Is there still a way for Adobe to reset the activation count for a legitimately owned perpetual Acrobat XI Pro serial number?
I can provide the serial number, proof of purchase/ownership, and other licensing details privately to an Adobe employee if required.