SysteMate 2000 - Constantly Boiling/Cycling

Hi,

Thanks for reading, I was wondering if anyone could help. My SysteMate 2000 seems to be consistently cycling hot water and demanding hot water from the boiler.

Despite the towel rails being off at the valve, Thermo being zero'd and the taps being off, the towel rail pump seems to constantly be cycling (this pump also seems to be on its way out) and the boiler is on and seems to be feeding the system.

I have flicked the switch on the timer to its down position, forcing the system to be permanently off, this has no effect, conversely, if I flick it to be permanently on, the system stays the same... as in, it is performing as in the electric board thinks the system is permanently on.

How can I further diagnose my hypothesis? Is this symptomatic of the SysteMate 2k?

I would greatly appreciate anyone's input on this.

Thanks,
Steve