my Glow worm combi has been having odd days when the central heating isn't working but then has been ok again after a day or two. But now it hasn't worked for the last four days.
Hot water is fine. and it will fire but then goes off after few minutes. If I turn it up the same thing happens and the same with if I turn the on wall thermostat.
Prior to it stopping all together I have had to have it turned up to half way to get the radiators hot,

Amanda, February 2017

Possibly the diverter valve is duff.

Glow worm offer a fixed price call out of about £300 including labour and bits. The only things not covered are the heat exchanger and the expansion vessel.

They alspo ooffer a minimum term maintenance contact that does cover labour and all the bits. This is for 6 months at £50 per month and drops to about half that if you want to carry n afterwards.

https://www.glow-worm.co.uk/homeowner/support/repairs/index.en_gb.html

XXX, February 2017