Biasi 24s?

My friend as a nine year old biasi 24s.There is no hot water and the heating has a mind of its own.(it came on when the demand was off) He has not got the manual for the boiler, it has had a new swith to control the heating from constant to timed in the last couple of months when the heating is selected it cannot be turned off. i managed to get hot water but the boiler only fired for a few secs and did not go to maximum burner?