My central heating has come on even when turned off at the main console and the thermostat turned to 0. It will only go off when I turn the console off at the mains which then leaves me without hot water. Any ideas?
It sounds like your thermostat is wired in by just two wires..ie it acts as a switch only.
If these two wires are by mistake shortened or bridged over then it will always be on as in effect you have bypassed your thermostat and rendered it useless.
This might be just one reason why you are experiencing the problem that you described.