Honestly, I'm not surprised at the response you got back, because you were looking at T-Mobile's Monthly Prepaid plans, and not their actual Simple Choice plans. At least you were able to get a more accurate response versus talking to support on the phone. At least I tried my best in helping you with your situation. Maybe some time in the future, you may consider switching to T-Mobile with their Simple choice plans, which are a better deal if you want 2 or more lines on one plan, but $50 for one line on the Simple choice plan just isn't as good of a deal in my opinion.
I'm also surprised, that you did not get a response from John himself, I guess the e-mails that he receives are also sent to other support members that make changes to e-mails that John reads, because I remember reading that John forwards e-mails with his solution to another team member that can put in the solution that he made. And most likely he can't read everyone's e-mail that gets sent to him.
-Michael