Can no longer see Home Internet account

When we signed up for Home Internet, I already had a T-Mobile Phone account, and for some reason I wasn't able to also sign up for Home Internet. So my wife signed up for Home Internet instead, using my email address for the account id (I manage all the tech subscriptions).

After sign up, every time I would sign in with my T-Mobile ID, I would be asked to choose between the two accounts associated with my id. I could choose my phone line account or the home internet account, and be directed to the appropriate account page.

Now, I'm no longer offered a choice - I'm sent directly to my phone account.

I tried to create another T-Mobile ID for the number of the home internet device, using my email address, but I'm told "Congratulations, you already have a T-Mobile ID -- sign in with your email address". Which obviously takes me only to my phone account.

I tried to create another T-Mobile ID for the number of the home internet device, and my wife's email address, but I'm told "We don't recognize that email address - use the one used for the creation of the line".

How do I get access back for our home internet account?