I've had 3 plusnet accounts develop faults over the past 6 weeks. One thing that has been consistently annoying to the point of losing my temper nearly, is that the CS reps have a tendency, not to have read the entire ticket history, and in several cases, have caused the fault detection to go into a loop (until I have lost it). On 2 occasions the ticket was cancelled because the rep didn't understand the fault even tho it had about 3 weeks of history attached to it.
This always seemed to happen when a different CS rep picked up on the response, rather than a rep I'd dealt with over several days.
So a suggestion, get your reps to read a history, especially if it's a long one.