Locked out from ATT.NET for more that 50 days, HELP!!!!

 I have had my att.net email for over 15 years and since it was established so long ago it does not have a recovery email or phone # set up.  I need to reset my password, but get an error message on att.com stating there is not enough info on my account and to call the 800 #.  I've spent roughly 10 hrs on the phone with ATT customer service in the past week attempting to resolve, with no luck.  Each group suggests a different solution and then transfers me to an another group who should be able to resolve.  They have opened tickets, escalated to support "experts" and each rep promises it can be easily resolved if I call a new department. The latest representative told me to call the Digital Service Center and request they send me reset instructions via US postal mail at my home address.  I called last night to request the US mail option and after spending an hour explaining the situation to them, the rep stated they could not assist and told me to call a different group later since that department's wait queue was so long.  I asked to speak to a supervisor, but they were unavailable. Furthermore, I have been a customer with ATT for over 14 years and while I understand the importance of info security, I'd like to believe there is a way to quickly resolve my issue.  As a final note, creating a new email address would be extremely difficult since I have used it for so many years and all my info, bank, health insurance info and several apps are tied up to this account.

Any help sincerely appreciated - thanks!