I cannot set primary account.

I set up my account 3 years ago. I was an international student at that time. So I did not have SSN for my account.

For now, I want to cancel the family plan from my account.

I went to the T-mobile store to get help. They asked me to call 611. But the customer service ask me for my password. I did not setup any password as I remember. They said they could not help me.

When I want to  set up primary account, it ask for SSN. When I enter the SSN, the system reject it.

Is there any way to resolve this? Should I always pay more money for the additional account nobody is using?