I have a problem with rooms too hot, so tried swapping the wax heads in the TRV's (Honeywell VT15) to electronic, adjusting lock shield valves, and wall thermostat improved but still not right. However there is one control I have never touched, the radiator water temperature control on the Worcester Bosch Greenstar boiler, maybe this can help? What I am guessing is with the thermostat in hall turning on/off (Honeywell Y6630D) the TRV heads (Energenie MiHome) are opening too much then can't close quick enough so radiator over shoots? Hence tried to slow radiators heating using lock shield which are on the feed side of radiators. So slowing down how quick the room heats may help? There must be a reason why we are allowed to alter water temperature, clearly the hotter the water the more heat radiated, but not sure what else it does, some insight please.