Drayton Digistat RF1 - more help please!!?

I cannot work out my Digistat RF1 wireless thermostat. Our heating has now been off for 2 days - I have been pointed in the direction of instructions (thanks to others on this site). I have a green light on when my heating should be on but no heat. The red light remains off (was flashing but batteries have been changed in the remote unit and then all was well until recently) and I have the correct display plus flame etc. Any ideas as to what the problem could be would be muchly appreciated...