My boiler has just started playing up. It's regularly serviced and up to date. Recently though it's started cutting out and I have no hot water or central heating. The reset button flashes red and F4 comes on the display. I can reset but sometimes it works after two or three presses, sometimes it can take half an hour, pushing the reset button, waiting, flashes again and then I push the button. Eventually the boiler kicks in, but only lasts a few hours then I have to start resetting again. Any ideas. Thanks-Anton