Got pulled in with a similar offer — fixed $50 plan, no surprises. After a couple of months, my bill was suddenly $67. Customer support said it was due to regional tax changes, but I hadn’t moved. I read through stories at https://tmobile.pissedconsumer.com/review.html and saw I wasn’t the only one. Some folks mentioned switching to prepaid to avoid it. I called in again and asked for itemized documentation. Once I pushed, they credited part of it and adjusted the plan. Haven’t had a random fee since, but I check every single statement now.