Thermostat on, boiler not on - house is cold.
I put in a Tado smart thermostat a few weeks ago. At first it seemed to work well, apart from the geo-fencing, which left everyone at home freezing and was quickly turned off. However I've noticed that if I manually change the temperature, either through the app, the thermostat itself or by asking alexa, the boiler does not fire. Tado will say the heating is on, but it definitely isn't. Sometimes manual changes will kick in about 45 mins later or not at all. The boiler has a red power LED, which isn't lit, which suggests to me that the thermostat isn't sending power to the boiler when it should be.
I know the boiler is working because it is heating water fine.
I've been back and forward with customer support with this, they've told me that they've looked at it remotely and it's working, but my freezing house says otherwise!
To briefly describe my setup: I have the smart thermostat starter kit, the thermostat is in the hall and communicates fine via the phone app or via alexa. The boiler itself has a very basic thermostat giving manual control ("on", "twice", "once", "off"). it is set to "on" all the time so the Tado has control.
Any suggestions? I'm kinda stressed because I'm working in the NHS, working crazy hours and my house is freezing!