Rebecca - since i wrote this post, and Tweeted some 25 times about the issue, I have indeed heard from Time Warner Cable, who also commented on my original post at What's Next Blog (I cross post to Ad Age)
And while it's true that anyone can impersonate a brand, and often does, the key is monitoring the brand 24/7. Bottom line, it took almost a week for Time Warner Cable to respond to repeated trashing of their brand on the Internet. That's like playing with fire - not good strategy.
"Time Warner does have a real Twitter account, @twxcorp, which actually seems to be fairly robust." But it wasn't monitoring "Time Warner Cable" on Twitter, on my blog, or on Facebook. Neither, apparently, were the ad agency, the PR firm, or anyone in corporate communications. Which is what led me to write this post. :>)
End of the story: A field foreman and a sr cable repair person from Time Warner Cable just left my house. They found the source of the problem, and they fixed it.
Now TWC needs to work on its online image.