I've never had cable service, but my DSL service though SBC sux ass, and I haven't been able to get them to do much about it. For one, they don't like the fact that I use a DSL router, and the one time I did jump through the tech support hoops, they made me disconnect it and install their proprietary crap on my PC.
When I was building my shop, the physical cable was in the way. I called the cable company (ComCast) to have them remove it, and I got the expected upsell. I told them I had no use for cable TV, and to just please remove the wire. Two weeks went by, and now it's really in the way - they're trying to set the trusses. I called and asked again to remove the wire, I got the sales pitch "well, we're having a special right now...." I cut her off and said "look, either you send someone out to remove the line, or I'll do it, and it won't be in a manner you like" When I got home from work, the line was gone