I've been with Telewest/Virgin for about 15 years now, and have found the customer service mixed.
On the whole, though, the actual products they provide, I've been impressed with.
I've been on the 20meg bb connection for about a year now. For the first six months or so, I was getting around 10meg, which isn't great for a 20meg service, but was a whole lot better than the 4meg I had before.
They did some work though recently, in preparation for the 50meg service, and since then I've had a fantastic connection - never less that 18meg and normally up at 19. Even at peak times.
And I've had only a couple of reboots required in a three month period.
On the whole, I'd say they were worth sticking with - once you're sorted, which sounds frustrating admittedly, I'm not sure you'll find a better connection.
good luck with it.
J
Jonathan Evans is Managing Editor of What Hi-Fi? Sound and Vision
What, from here?
With these feet?