how do you control man heatline condensing boiler?

I have a heatline condensing boiler. havent a clue how to control it. just use the thermo on the hall wall. Set it to 20o and it worked. Until two hours ago when all stopped. All the lights on the control panel went out except the green light. Tried the reset, by putting it back to O, then put the switch back to hotwater/central heating, and it workued for a short while, then stared to hunt. Starting up then shutting down then starting up. Can any one help please.
Your name: brian