Hi , do you live anywhere hanger lane , London?
If you do , there's ac place that does reconditioned boards cheap , but I don't know what goes wrong on them . but 4 is nuts. There must be something else wrong . are you sure you don't have a water leak that's dropping onto the board.
No, no water leak affecting the boards, nor anything else environmental which is making them fail... just a run of particularly bad luck it seems. I'm an electronics engineer and I could track down the faulty part with a bit of time.... I was just trying to short-cut finding the specific component. Not like WB to be that bad, but I've heard the RSF 24i and 28i are notorious for it.
They are pretty bad , but i think most boiler engineers dont have the electronics knowledge to work out the faulty component unless its obviously burnt out.