Bosch M10 Timer problem 3 pos switch is ON regardless of position

[flat4kendal]

I have a 28i Junior with M10 manual timer.
The boiler has been operating fine and I'v been using the the ON and OFF positions on the M10 timer to switch the heating on and off rather than using the timer.
Yesterday the when i turned the switch to OFF it didn't turn the heating off. The only way I could turn the heating off was to turn the boiler off at the wall.
Any hints or tips ?

 

[lame plumber]

call a technician to sort it out

 

[ShaunCorbs]

as above you need to be gas safe registered to work on gas appliances but sounds like

 

[lame plumber]

as above you need to be gas safe registered to work on gas appliances but sounds like

OH No it doesn't!

 

[ShaunCorbs]

OH No it doesn't!

:winkiss:

 

[Rickster123]

As above. Please read forum rules.