Q Second Party T-Mobile Carrier Locked S5 topic

My son bought a Galaxy S5 from a pawn shop but when he put in his Sim Card it was Carrier Locked. He went to T-Mobile and was told that the phone is locked by them because the previous owner had not paid his commitment on the device and there was nothing they could do for him.

It there a way to unlock this device? I have been searching but haven't found anything related to this type of locked device.

Suggestions and help is appreciated