The MSISDN is already registered to another IAM user account

Exact same problem as of 7/12/2022.  Almost the same case as those above -- returning customer from an experiment with a different carrier (trying to save a few bucks); well, their [the other carrier] service sucked and I am coming back to T-Mobile after about a 4 month break in service.  

But, I have been on the phone with 611 for the past 30 minutes and I have even given them the link to this Community post -- it seems that they *STILL* don’t have a use case in their playbook for how to remedy this.  

I will update this post if I ever get resolution.