I have just had to pay Talktalk £70 to get out of a rolling 18 month contract after they didn't send (or I didn't receive) a letter from them. Apparently they only allow 7 days for you to cancel or 14 days if you ring and say you didn't get the letter.
But thats for cancellations I don't know what they do if you instructed BT to take the line back and that process took longer than 14 days, another 18 months and a £70 bill perhaps?
During the entire 18 months of TalkTalk hell my average broadband connection has been under a quarter than that (upto) advertised and I have lost phone and broadband connections on a number of occassions. Once for over 2 weeks (no refund).
There customer service is shocking, even a basic thing such as not saying their customers services dept is closed before sending you through a hideous number of options!!!!!!
I would advice avoiding TalkTalk like the plague.