Help! - VAILLANT ECOTEC PLUS - not firing - brrr

Hello
Wondering if anyone could shed any light on my non-firing boiler on this chilly afternoon!

It's a Vaillant ecotec plus.
The display is alternately flashing 71C and then all the symbols together, no discernable fault code, along with the flashing screen there is a clicking sound that is a bit like a car indicator (or maybe a boiler trying to fire and failing). There is 1 bar pressure, and if I hold down the + and - button together it says SF.h

Is there anything else I can do?

Many thanks
Peter

Well holding the + & - together is only setting the boiler to max output

Try turning off at the fused isolator for 30 secs. If this does not work and with the display falt you describe I think a call to Vaillant service is needed.

Thanks Dave,
Just tried that, but no luck.
Thanks for the advice.
Peter