I have Internet access at home once again.
If I weren't already an NTL customer I would certainly not have joined up on the back of their recent performance. Every step of every action has been marred by technical and manual failure making the whole process a nightmare.
Finally, about 5 minutes ago and over 3 weeks after I first notified them I was moving, I was able to complete the process for re-registration with my new cable modem and gain access.