I have TWC... haven't had many issues, and they've been pretty responsive when I've reported a problem. AT&T reps knocked on my door a while back... ended up going online and their deals are pretty frontloaded and deceiving (more than usual for the industry). It all seemed to wash out after 6 months or so.
As far as customer service though, I always use online chat and can easily exhaust the first several things they ask everyone to do, so I can't speak to call volumes and cusfomer service over the phone.
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