I would agree with stem. A wireless radiator zoning TRV pack does allow control of every room together with a controller
but not cheap. There are also replacement heads
which give far better control of each room.
I have considered two thermostats one upstairs and one down stairs to stop overheating due to the chimney effect in my case it would reduce the temperature down stairs after a set time.
What you need to look at first is how the whole system works. Pre TRV we would place the thermostat in a room with no other heating and alter the lock shield valves to adjust all other rooms to get a percentage of the heat available.
After the TRV the TRV did all the controlling and the room thermostat was only really to allow one to turn off the heating in the summer as to if a thermostat was required depends on how good the anti-cycle software is in the boiler.
The wireless TRV has been used to switch off heat to rooms when not used. For example bedrooms during the day. With TRV you should have also a by-pass valve so if all close hot water goes direct back to the boiler.
In the main the TRV became essential with the condensate boiler as rather than simple on/off these boilers adjust flame hight according to return water temperature. Poorly set lock shield valves can cause the boiler on first switch on to start reducing flame size early.
In fact most the central heating systems I have been called to with cold rooms it has transpired either lock shield valve not set i.e. system was never commissioned or some one had played with them. The other is muck in the system blocking the lock shield valve.
So step one find out what system you have. Step two explain the problem. Step three the hard bit decide which advice to follow.
On the 27th I will attend a lecture on the 3rd amendment to wiring regulations. And this is typical for electricians we have to keep up with latest technology and regulations. Unfortunately it would seem plumbers don't keep themselves updated in the same way. Some electricians are the same.
"I have done it this way for the last 30 years I am not changing now." is unfortunately all too common. I have found on here some of my ideas are wrong because something has changed. Once you identify the problem your job is to work out which advice is valid. Good luck.