Hi I've been having problems on and off for weeks with my boiler which is not even 4 years old yet, where the reset button keeps going red, showing that the heating and hot water is not on, basically the boiler is not working and the 70 and 80 lights are flashing, showing the flame is undetected. We have been able to press the reset button and get it working again but gradually this has not worked and now we have had no heating or hot water for 5 days. Our plumber has changed the flow sensors but this has not solved the problem, anyone any ideas?