TMobile “Free” Third Line

When I first joined T-Mobile about a year ago I ported over two phone numbers from Verizon and was offered a free third line. I took it and forgot all about it. My bill was always around 150sh

Fast forward a year I ended up taking a good deal for new phones from AT&T and ported these numbers over. I thought I was good and I just got an auto pay for 120.00 from TMobile. I called and they are still showing the 3rd line as active. However they could not give me any information over the phone as I do not know my account pin.

They told me I'd have to go to my local retail store for assistance. Has anyone had a similar issue? Idk if that was just a final bill or if they are charging me for the third line..idek the number for the line as it was never used.