We had an intermittent problem with the service several months ago. This continued for maybe two - four weeks and the cause was that we rarely had any watchable television at the weekends for that duration.
I eventually "threw the head up" (I'd had enough)

and complained to CS and faults. Apparently it was traceable to a nearby cable box and engineers were attempting to fix the problem but could not isolate it - in other words it was not an easy fix.
A member of staff from NTL called soon thereafter and arranged for someone to come out and check the cabling around the house as we would be very susceptible to faults (because we have telephone, 3 STBs, and Broadband)
This person, whom I assume was a manager of some description kept in contact with me throughout this time and offered to pay compensation for the loss of service during the 2/4 weeks of disruption.
If I remember correctly, we got a reduction around the value of the Family Pack (£28). To be honest, I wasn't looking for compensation and I thought, and still do think that this offer was generous as it was only the television service that was disrupted.
What can we say about this?? Some sections of NTL are generous, kind, and full of goodwill. If you treat them with respect, it is more than likely that they will treat you the same.
James