How or who can I get to fix my Drayton Wireless RF3?

I moved into a flat with a Drayton RF3 wireless system installed. Only problem is the SCR does not seem able to pick up signals from the RF. I can override the SCR to get radiators on but am unable to programme heating. The boiler has a normal manual timer but this appears to be disabled. Temperatures and timings can be set on the RF unit but the SCR red light is constantly on and thus indicates no signal pick up... I have tried changing the batteries but no change. Who should I get to fix the problem? electrician? heating engineer? Am short of cash and dont want to spend £55 on a call out to be told nothing can be done. Thank you
Catherine