Thermostat not controlling the boiler

Ugolino5

I have installed the wired thermostat but it doesn’t seem to control the boiler. I set a target temperature, but the boiler does not shut off once the target is reached - it carries on heating and pushes on to higher temperatures. This is true in the smart schedule and manual settings.
Can anyone help or guide me with this?

policywonk

Whats the boiler and is it running in relay mode or digital control mode? Is there a zone valve handling central heating? Come back with this information and we could think this through with you.