Billing Madness

Okay, where to start. My mother's had Verizon DSL for almost a year now. In that time, no exaggeration, not a single month has gone by without a billing mixup on Verizon's end. Like clockwork, at the end of each month she has to get on the phone, and clear things up for another month with their confused representatives. But she's had a new problem recently. A couple months ago, one of the representatives told her that Verizon had stopped including internet charges on monthly phone bills, and if she wanted to have her internet turned back on that month, she needed to start paying through a credit card instead. She was very reluctant to do so after all the previous mix-ups, but eventually gave in after not seeing any other options. Verizon hasn't taken money from the card once in the months since then (even though she'd love for them to), and the internet bill keeps growing and growing without the service being shut off. Before she puts herself through the usual song and dance, I wanted to see if I could find any answers online. So does anyone have any ideas or suggestions at all? Thank you.

Verizon's internet speed has been great from the beginning, but they've had the worst service either of us has ever experienced. I'd be really surprised if she doesn't jump as soon as her contract's up.