temp control?

British Gas homeserve replaced defunct honewell control for a British gas Thermostatic temperature control system (wireless thermo/roomstat . Each of 11 radiators has a TRV.
Q: Would they be at war with each other . Should this unit have been fitted.? The former was a wall timer/temperature control by Honeywell side of heater. And this could not be replace like for like as engineer said cables still live because it meant changing the back box on the wall. I offered to Isolate ALL electrics by turning off the main switch. No he talked me in to the wireless system. Should I have said NO! I want like for like as I can turn off electrics while back box is changed…. I don’t think he wanted to do that.
Many thanks