well if you get no channels at all with ntl or telewest you must be c&w have you got a legit box you can check netid or a neighbours?
then installation > factory default setting > ok > automatic search > make sure it is on 2 c&w and network > then press green on remote for netid > scroll up to netid highlight it and press okay then channels should scan in if your connections are not duff bad splitter or duff cable running from splitter to box perhaps evn take splitter of and try direct connection from street to box.
When I choose ntl or telewest I dont get Net IDs anyway. I only get Net IDs when I do C&W. In the past when I have been doing c&w channels have been coming and freeview channels worked. Even now I do c&w; I do get channels but they don't work.