a new pcb for a baxi boiler is £75 so i would imagine it will be roughly the same. from my experience wid combi boilers i would say its fubarred get a new one and be done wid it, it will be cheaper in the long run. i used to find my combi boiler was always temprementle when the climate changed, summer to winter or vice versa. something to do with build up on the filters or summet, just a thought as the last week it has become noticeably colder, well it has in the lake district anyway.