Locked out — 2FA code goes to an email address that no longer exists

Hello,
I'm posting from a new account because I'm locked out of my original one.
My old account was created years ago with an email address that no longer exists. I still know the password, but after logging in, Box sends a 2FA code to that deleted address, so I can't complete the login.
The account holds over 1 GB of important content, mainly workshop recordings (.mp3 files).
Could Box Support please help me verify my ownership and regain access, ideally by updating the login email to my current one? I'm happy to provide verification details privately.
Thank you very much