Glow-worm 18sxi problems - HELP!?

Hi
We bled the rads on Friday evening, lots of air in system.
Later that evening boiler refused to work, 0.4 bar and red light on.
Anyway googled the problem and found this link : http://www.howtomendit.com/answers.php?id=179880
It worked fine, much to our relief as it was really cold last night. Got pressure up to 1.1bar and then by this am it was back to 0.8bar where it usually is.
Anyway, our hot water / heating is due on same time, but you can always boost one or other if you need more, until this evening.
Water will not boost, in fact boiler doesn't even spark up, nothing at all, but the heating will on its own?
Anyone know why?
Thermostat is set at 20deg c, dont want heating any hotter and obviously when I put heating and hot water on (the only way it works!) it turns itself off in 5 mins as the temp is already where it should be...
We have an immersion but that is very £...
Any advice???
Many thanks....