Hi my Vokera Compact HE is failing to ignite therefore having no hot water or central heating.... Previously the hotwater was warm then it would turn cold then heat up again and now its not putting out any hot water.....The boiler is going through its start up sequence as normal i.e. pump is running, fan is blowing & then a click (which I assume is the air pressure switch), the next step is usually Ignition?? which I usually hear a series of clicking sounds for a few seconds, but I no longer hear this series of clicking sounds....... how do/can I resolves this!!...........I should add that the green light is flashing which (from what i've read) is no fault...... Thanks Lee