I had an experience very similar a few months back. Ex wife signed up for some garbage, gave my number, and the charges showed up on my bill. Fixing it was about a half hour of getting customer service on the line (Centurylink) and the end result was blocking all 3rd party charges and all fee charges in general (so, no 900 numbers for instance).

I only say this to add one thing: The people at customer service were *AWESOME*. She actually got on the line with the third party company and (while I listened) demanded that they refund the money that had went out the previous month that I had missed. This lady really went to bat for me, and even went so far as to apply some discounts to my account to offset the time I had to wait online (something like ~$40 over a year).

I know, incoming mod downs for actually being happy with customer support, but damn. I see so many of these replies where everyone claims these people are the scum of the Earth. Fact is, the last few months every customer support person I've had to deal with (and it's been a few: Centurylink, DirecTV, AT&T) have gone above and beyond to make sure I was happy when I got off the call. Try it sometime instead of sitting around bitching about it on the internet.