I am experiencing the same issue since updating my BT-ID (on BT's instruction) to the new required e-mail format.
At present I cannot access my MYBT account and I cannot view any of my Bills.
I spent over two hours recently with the Helpline Chat-Bot ) trying, ultimately unsuccessfully, to get this sorted, and ended up as a very Unhappy Bunny with the following referral to a "higher authority">
(Fri, 3 Jul 2026 18:09:39) BT : In order to get BT ID prioritized & to acknowledge your concern and take
feedback to serve better. I have logged up the complaint and the Complaint
reference : ************
If this means anything to anybody, I am happy to discuss this further.
[MOD EDIT - REMOVED PERSONAL DETAILS]