How can I fix my Ferroli Boiler 80E 0008L71559?

I have three probelms with my boiler all happened at the same time? My boiler won't stay on it keeps igniting then going off even from when the heating is first turned on, it stays on from anything to a few seconds to a few minutes so the rads are only ever luke warm and when it is on timer and the little bulb is showing when it is set to go off it won't turn off it just keeps dong the same. Also when I turn my hot water tap on the burner does not ignite and therefore I get cold water until it decides it wants to ignite which can be a minute or more.