Try ringing either 150 from an ntl phone or the 0845 number, there is a message saying that C/S is closed but if you stay on the line it does ask you if you want to report a fault, press 1, and it will take you through. It is faults you need not CS anyway, good luck and hope you get the channels back !
Just to confirm that CS or TS don't deal with things like missing channels, no pictures etc, it's a fault so you need to speak with Faults