Central heating won't turn off

Amberlee_2

I have a Worcester Bosch Greenstar boiler- condenser and it is the type with a cold water tank in the loft. It is quite a new boiler.

The timer for the boiler does not work, in that I cannot set it to come on and off at specific times, so I have the heating on constant and control it via the room thermostat- turning it up and down as I need to. This is a temporary fix until I can afford to replace it.

This morning, the heating would not turn off. I turned the thermometer right down to 10 degrees and it still carried on heating, even though the house was red hot.
I turned off the heating at the timer switch and it has finally switched off.

I have no idea about DIY and am on a tight budget- does anyone have any idea what the problem could be and if it is expensive to fix?

ic

Is the room thermostat wireless? Has its battery gone flat?

Amberlee_2

Don't think it's wireless- the house is about 35 years old and the thermostat looks original to it.
there are no batteries- it is just installed on the wall in the hallway, I assume there are wires connecting it to the boiler.

The control is quite new- well, about 5 years old.
It did turn off-finally- when I switched it off at the control.

The thermostat clicked as turned it down, but the boiler just kept going