False Data Roaming Charges

I’ve been charged $24 for data roaming charges for 3 months now. The first month, I didn’t notice it. The second month (beginning of October) I called to complain; I would never have signed up for such a service. I requested that it be removed and I be refunded. I was asked if I traveled internationally. I said yes, but I did not use my phone. I had my phone with me for the calendar and clock. I didn’t need to make calls or send text messages, nor did I receive any. I was told they would remove the charges and investigate why I was charged in the first place, so it wouldn’t happen again. They called me a week later and left a message that they were still investigating and would call me in a week. They never called. I naively assumed that they were still investigating, but had removed the service and would refund the charge. When I saw my third bill on 11-4, I tried to call repeatedly. I kept getting a message that they had too much call volume to answer my call. I tried their online chat service. I never got a representative for several minutes. I tried to contact them via web or email. I found no address or web form. Once I reached them by phone the same day, I repeated the entire story. I told them even if it had been accidentally activated, I don't need the service; remove it and refund me. The woman told me she couldn’t remove a valid charge. I told her to get her supervisor or I would file a complaint with the Attorney General and Better Business Bureau. She did. The supervisor didn't know anything yet and asked me to start over again. Then she told me she would have to end the conversation if I was not polite. I’ve paid for these erroneous charges because I’m signed up to auto-pay. I’ve just removed the auto-pay service. I won’t pay my next bill unless it reflects a 3-month refund and removal of the service. I’ve had an account with T-Mobile since 2005. I’ve never signed up for such a service or disputed a charge. I cannot take my business elsewhere as they have me locked up in a contract.