How can I stop my Drayton digistat+2RF from staying on? ?

I have just moved into a new home and my heating keeps coming on when it is not programmed to. It comes on at 1am etc. I have a Drayton digistat+2RF and a Worcester Bosch boiler in the loft. I've had a heating engineer out who says the boiler is working fine and I paid for him to reprogram my digitstat. Then the same night it came on as before. Electrician has been and done the same and that hasn't worked. 3 family members have also reprogrammed it and it's still coming on. Help!