At the point where I fired them, about seven years ago, they knew how to accurately deliver TV service, but not Internet service.  

Them: "We can see your modem."

Me: You're having an ARP storm that's eating up all of the bandwith, with reflected traffic to boot.
Them: "We can see your modem."
…
Tech: "Yeah, we have all sorts of problems with [the large apartment complex half a mile distant] all the time.  You're on the same circuit."

Google Fiber has been much more reliable, with no "everyone just got home from school" or "it's time to stream Game of Thrones" type slowdowns as well.