worcester 24CDI - possible problem with pcb?

Hi,
I hope someone can help me confirm a possible diagnosis!

My combi-boiler was working well until a few months ago, when the heating started coming on when not programmed to, and while the heating dial was in the off position. (At these times the radiators get incredibly hot and the hot water becomes scalding.)

I've resorted to turning the boiler on manually when I need heating or hot water, but I really want to set it to work automatically - especially as at times I've switched it on and the central heating light will flash and the pilot light fails to light first time, so I have to keep over-riding it until it starts to work.

I've been reading some related posts and I think I may need to replace the pcb?

The boiler is a worcester 24CDI RSF-LCOMBI

Thanks in advance!