CenturyLink is totally shady. My wife just yesterday spent a significant amount of time fixing our phone bill. She decided a couple months ago to upgrade to a "fixed" bill plan (apparently they've been raising our prices $10/mo every year for the last few years). This plan price won't change until we change the plan. It's bundled with their internet though, but my wife told them to not send the modem because we weren…
The sad truth is that these telcos will systematically screw millions of customers with shady fees and fraudulent billing practices, but when the FCC gets involved, they are facing potential fines of tens of thousands for each infraction, so they'll bend over backwards to get you to drop the complaint.
Try it sometime, it sucks that it's necessary, but you'd be amazed at the results.