I'm with TalkTalk and as Paul has said ive had problems with them.
its almost impossible to get through to a human being, i spent 8 days with no phone or internet and after their first repair which lasted 2 days i had to go through it all again with them.
the end result is my internet is half as good as it was and i got charged eight pounds on my bill for ringing to tell them about the fault.
i certainly wouldn't recommend them and i will change when i find a good deal