I arrived back from holiday to find the house like a sauna, everything in the kitchen too hot to touch, cutlery scalding hot etc. My central heating was on full, and must have been for some days.
Quick check of the thermostat showed it was working fine, but turning the central heating timer on or off had no effect. I have had to remove the fuse to the boiler power. Two days later with all windows open 24 hours a day it is still unbearably hot.
I had a look at this question, but the symptoms don't seem to match. If I pop the fuse back I have scalding hot water and radiators no matter what the settings on my central heating.