I assume it's the same as when I worked for the phone company, more than 10 years ago, but the other hard part for a lot of customers was understanding that they had to call the company that put the charge on the bill to cancel it most times. Regular customer service phone company employees couldn't do it, although removing the charges wasn't a big deal so long as the dollar amount wasn't huge. It was amazing how long some of these charges could be put on before someone caught on, and then expected all of them to be removed, months later.
It really pays to review your bills every month. Very simple to do, and then you know what it should look like.