Ok so here is a possible solution, but one thing is clear, you are not being charged to use your wifi. Who ever said you were doesn't inderstand how networks function. So what is happening with the tmobile network is that tmobile, even if its to their knowledge or not, is that your phone is accessing it on its own. Tmobile has no idea at this time why that is, because I had the same $50 charge to my bill. And because the iPhone is not an authorized phone they are pretty clueless. But do this: check out your bill. Is it accessing at odd times? Say in the middle of night when you are asleep? And if you look at the times on your current usage is it coming up at time one the hour and on the minute? (e.g. 10:40pm, 11:40pm, 1:40am, etc.) That's what I noticed and got my fees all waived. This is a pretty unknown problem to them, and the representative I talked to tried to stop the pay per use from being accessed, but my phone continued to access the tmobile internet network. The next best thing to do, next getting your money back, is to take the other people's advice about the data blocker and use it. Tmobile has no way to stop it from charging you, even if you have family allowance, as I do. I hoped this has cleared things up.