britony se 80

[livportchest]

I have a britony se 80 boiler and it is not responding to the wall thermostat control. That is if I turn down the temperature the boiler continues to run.
If I turn off the central heating at the boiler and then turn back on again it does switch off, resets and will fire up again when I turn up the wall control.
You can hear the wall control clicking in response to turning it and you can here there boiler respond as if it was going to turn off but it still runs.
Any Ideas as to where the fault may be?
Many thanks for any responses.
Peter

 

[Agile]

have you measured the voltages at the call for heat terminal in each condition?

 

[livportchest]

Thanks for the response.
No I have not checked voltages, I have not removed cover yet, just wanted some clues as to what it may be.
The fault does seem to be intermittent, wondered if it would be the temperature sensor or the overheat sensor.