Unauthorized calls to United Kingdom?

I woke this morning to alerts announcing my account was suspended for making nearly $800 in calls to the United Kingdom. I have never called any other country in my life, don’t even know how. These calls where allegedly made from my number, of course they weren’t. I contacted Customer Service, their sole suggestion was to add a $25 monthly service to my account which allows international calls. Needless to say, this suggestion was insulting considering my insistence I had not made these calls. Failing to reach a solution, their other suggestion was a one time courtesy cancellation of the charges, a solution that would not stop future calls, I have subsequently invoked the dispute resolution mechanism of my contract. Has anyone had problems with international calls being made on their account?

Edit: T-Mobile suspended my account for unbilled charges. When calling to get it resolved, the fraud department weighed in and determined the charges where fraudulent and voided them out. So far, so good.

Final update: T-Mobile legal department received my written complaint and began an investigation. They called and assured me all unauthorized charges would be voided, and promised to handle it personally should the fraud department not remove them quickly enough. They stated the charges would appear on my bill, but that the auto-pay amount would be for my standard service. They also promised me a free month of service by way of an apology for dropping the ball so badly. Further, they assured me the representatives and supervisors in customer support would be retrained to handle this issue more promptly in the future. The department said it was an issue with Digits and my T-Mobile.com account. I had already changed all my passwords and keys for my account. This resolved all my complaints, and assuming the actions promised will be delivered, I now consider the matter closed. Thanks everyone for responding.