I have a Halstead Ace High combi boiler that keeps cutting out when the hot water taps are running it also does it when the central heating is on. It has also taken to sometimes firing up for around 5 seconds just after a hot tap has been turned off. The system has been cleaned and the air pipe tubes have been cleaned through with compressed air, sorry as you have guessed I am just the unfortunate owner of the boiler not the Corgi engineer. The Corgi engineer has called 3 times and each time the darn boiler has performed without fault. Has anyone any idea what could be wrong please.