EA Account locked 5 years - verification keeps failing (Xbox)

Hoping a mod can help me get this escalated properly.

My Xbox gamertag is permanently linked to an EA Account that is registered to my old high school email address. The school decommissioned that mailbox years ago.

I want to be clear about one thing up front, because this gets misdiagnosed every single time I ask for help: I CAN receive password resets. They come through to my phone number and to my other email addresses. I have reset the password many times. Resetting is not the problem.

The problem is what happens after that. On Xbox, launching an EA game returns "your login credentials have expired," and I still cannot get into the email. When I contact support to get the registered email updated to an address I actually use, I'm put through an identity verification step — and that step has failed three or four times across roughly five phone calls over five years.

The question I'm always asked is to name a game I purchased on the account. I answer with games I genuinely bought and played, and I'm told the answer failed verification. I've never been told which detail was wrong or given a way to supply different evidence.

For context: this account worked normally for years. I still have physical discs for games I played on it, including Battlefield 1 and Rainbow Six Siege. Then one day it simply stopped working, with no warning and no notice from EA.

One more detail that may be relevant: on the Xbox side, my profile appears associated with my current Gmail address, but the EA side still shows the old school address. The two don't match, and I have no way to change the EA side.

What I'm asking for:

1. To have the registered email on the EA Account updated to an address I control.

2. To be verified using something other than the name-a-purchased-game question, since that has now failed several times.

3. A case number, so I'm not starting from zero on the next attempt.

What I can provide privately: proof that I control the linked Xbox gamertag, the original registered email address, physical game discs in my possession, in-game details from when the account was active, and approximate purchase history from that period.

I understand account details can't be discussed publicly. I'm just trying to reach someone who can look at this properly instead of restarting the same verification loop. Five years is a long time to be locked out of games I paid for. 

Thanks.