Erratic Boiler cut out (and in laws)?

So it's snowing and we have my in laws staying for Easter weekend - what's the last thing we need? A fault in our Vokera combi boiler.

The boiler randomly cuts out but then restarts erratically once or twice a day. The red light on the wall switch is still on, but the whole unit goes dead - not even a red light on the front - and the clock stops working.

We're covered by Heatgguard but can't get hold of anyone for love nor money this weekend.

We've tried turning on/off and the pressure is spot on (1.5 bar) but no joy. When it does (spontaeously) turn on all is fine hot water and heating wise - we've just no idea when it'll turn on/off.


Many thanks for any help/pointers you can provide - we're chilly!