Why did Tmobile start charging me the 3rd line and the customer service can't solve my problem?

I'm not crazy!  You have clearly explained what happened to me on my 55+ plan.  I only had TWO lines and they promoted 3rd line free.  All of a sudden my $70 , month bill changed to$90 month. 3rd line $20/month extra.

When I called about it, I was "convinced" to believe that it's $90 for 3 lines.  Not $35 each line. Plus $20 for the third line after promotion ended.   It was FREE!!   I've tried and tried to drop the 3rd line but they refuse and say the best option is to put a suspend on it 3, months at a time.  A phone I don't use!  And still pay the $10 month for keeping the number... That IV don't use!!