Biasi Combi Boiler - CH won't turn off!

This is a really odd problem and one that both manual's troubleshooting section goes nowhere near. The Thermostat is a wireless one and it has lately being acting strangely, if you manually/programatically cause the target temperature to go above the room temperature the Central Heating clicks on. All is good, but if the temp is reached, or you set the target temperature to the minimum (10C) then despite the thermostat's display suggesting all is good (target and current temperatures shown on the LCD are correct and as expected) the Central Heating does not switch off, instead it merrily ticks way to itself for an hour or six before finally realizing and stopping. You can manually enable/disable the C/H at the boiler easily enough. None of the lights on it are flashing any error codes. The hot-water works absolutely fine throughout and i even tried replacing the thermostats batteries with brand new ones.

Basically the boiler seems to be respecting the Thermo's ON signal and ignoring any OFF signal it receives!

Is there a simple way i can just reset/turn-off-and-on-again the boiler to try that? :-)