Siemens remote thermostat RDJ10RF doing opposite to setting?

My Siemens remote thermostat does the opposite to what i set it to. The time i set it to turn the heating on, is actually the time it switches it off, and then the time i set it to turn off, it turns on, and as a result my heating is on all day. I have tried to reset the whole system, but it didn't help. this worked fine before but all of the sudden the heating started to come on at 8 at night instead of switching itself off. anyone have any ideas?