Tado Thermostat is not switched on but my radiators keep heating up
I live in an apartment building on the 6th floor. We have a shared boiler.
I installed a Tado Thermostat and two Smart Radiator buttons. I did the installation myself, replacing the previous thermostat: Honeywell T6360. I did the wiring myself, but is correct. The thermostat has been working since it was installed in January 9, 2019.
The smart radiator buttons in the bathroom and in the bedroom work perfectly. The heating switches on and off when it's needed. But the thermostat in the living room remains a problem. It keeps on heating, even if the desired temperature is reached and the buttons in the bedroom and bathroom are off and do not heat up.
In reality, this means that my radiators in the living room are on all day, even though I'm not at home and the thermostat and the buttons are set to 'don't heat up'. While the minimum temperature in the living room is set to 16° and the maximum temperature to 19°. But it stays between 21° and 22°, all day long. I don't understand how it is possible that the radiators in the living room continue to heat when the thermostat is not even switched on. When I come home it is warm in the living room and the radiators are hot. While this is not the case in the bathroom and the bedroom.
The last day that the thermostat really did its job was November 1st. Since then the radiators heat up even when it is turned off. Is this a connection problem? Would there be something wrong with the wiring, the connection with the boiler?
I have already reset my smart thermostat, removed the batteries but that doesn't work. For the time being, I have turned off the radiators in my living room manually. But that's exactly the opposite of a smart thermostat, isn't it? What goes wrong here?
I've been mailing the helpdesk about this since November 7th and I keep getting the same answers while there's clearly something going on.
I'm at my wits' end and I just want help and different ways to solve this problem.