ATT.net email address from when I had U-Verse

I've been using my att.net email address for over 15 years and have had the email account set up on my iPhone in the default iOS mail app. The iOS mail app prompted me to reenter the password and it won't accept it. So, I went ahead and tried resetting the password but since I forgot the answers to my security questions, I am unable to do so. I have tried calling ATT customer care on three separate occasions and I can get no assistance whatsoever. The 1st call was a "I can't help because your email account is locked for 24 hours." The 2nd call was I need your Uverse account number from the account I had many years ago and no longer have which I couldn't find at the time. I was able to find it the next day and called in for the 3rd attempt and even after getting the Uverse account number I couldn't be helped once again.