well like tmobile said, either you have the data plan or you dont. Its not like verizon where you pay per mb. So if they charged me something like that I wouldnt pay because I dont have the data plan so they cant be charging me, they dont even have any plans for per/mb data plans, so technically they dont even have a price to charge you. Its not your fault their data leaked. But this was probably different 5 years ago, they mightve had a per/mb plan back then