I contact them every 6 months or so to beg, cajole, and threaten to take my business elsewhere (to whoever is actively advertising a good deal at the time). They usually find a way to hold or lower my bill. Sometimes I have to call back a time or 2 until I reach someone who will "work with me". Sometimes after I've received a 6 month "discount", I have to let the bill go back up for a couple of months before starting the process all over again.
When they increased my bundled package from $100/mo to $150/mo, I called to tell them about their shOtty business model, and they told me the only way I could get the rate back down to $100/mo was to discontinue the service for 6 months, then sign back up. I told them to go ahead and discontinue the cable tv part, (had all kinds of problems with that), then soon told them to discontinue it all when I moved.
Businesses know people don't like change, so I fail to understand why they would want to drive away people from their service, and risk them not returning because they find another company to offer the same services. I have friends, who discontinue the service in one person's name, then re-up in the other person's name. I guess anyone could do that by changing the service to a different family member's name. Just an idea.