Hi
We have a Potterton Suprema boiler, a Potterton EP3002 wall timer and a Wickes wall thermostat.

The heating switches on OK according to the timer schedule but fails to switch off when it reaches the right room temp set on the thermostat so we just get hotter.

I had to have a new thermostat for some reason but I seem to remember there being 3 wires into the stat but there appears to be only 2.

Is that right? And would the missing wire be the one to turn off the heat?

(Pictures attached)

Thanks

Daren