ferroli 77 ff combi boiler

[semple2174]

hi there, i have a ferroli combi boiler model 77 ff, 3 weeks ago i noticed that when on hot water setting i was only getting a small amount of hot water and then the water was cold, now i am finding that the boiler won't fire up at all, the pilot light is on, but when i put the setting onto continuous heating and hot water i am only getting a clicking and buzzing noise, i have investigated this clicking and buzzing noise and it is coming from fr2 relay on the pc board, it flashes initially and then continually clicks but won't fire up, when i turn on the hot water tap fr4 relay also clicks and buzzes but still doesn't fire up, what i would like to find out is, do you think by replacing the pc board it will cure the problem or is it likely that something else is causing the relays to go go faulty