I've had a look around recently about which ISP I'd replace ntl with if I became too annoyed, and have decided that I'd probably use
http://www.demon.net/
It requires a BT phoneline, but has no engineer costs due to them sending you a modem and adsl phone filters in the post and is £20 for up to 2Mbit (the speed depending on your distance from an exchange I'd guess)
Another reason I wouldn't mind using them is that they are as old as dirt as far as UK ISPs go and they have a good customer service reputation (which, with all respect for the guys who are on here, ntl do not).
Lastly (and most importantly for you) it says unlimited in the ads.