I have a TM4-TS which controls various radiators on all four zones. The unit is set in 5/2 day mode. I am adjusting the switching times and want to ‘delete’ the second on-off time on one of the zones (set it back to —:—) but can’t work out how to do this. Setting both on and off to the same time doesn’t work as it switches on (and not off). Please help.