I sent a letter to the T-Mobile corporate office reporting the agent who hung up on me as well as disputing the charges and requesting a detailed report of my data usage for that time period.
Today I got a letter from them apologizing for the poor customer service but not offering anything other than a promise to forward the information to customer relations. Not impressed.
As for my request, they claim they can't provide that information because they don't have access to it. They also claim that I can go online to my account and view the IP addresses of sites I've visited. I have looked EVERYWHERE on their site and can't find any place to do this. All it will show me is date, time (only on current billing period, not past ones), service (mobile broadband in this case), amount of data and how it's measured (in mb), and any extra charges incurred. Nothing else. Their site is pretty badly designed, but I really don't think I'm missing anything on there and Googling turns up nothing.
I just can't even at this point. I'm thoroughly disgusted by how they've handled this in general. My last option is calling corporate directly and trying to get a live person to talk to here in the US, I guess, but I'm not holding my breath on getting this addressed properly. I find it very hard to believe they can't access that information and send it to me and by now I'm pretty sure they're lying through their teeth about the whole thing.