Anyone recommend a heating engineer or any advice on my problem?

Hello,

So my heating is not working! Middle of winter, nightmare! Brief description of the problem - boiler is a vaillant ecoMAX. Put the heating on and it either goes into fault mode (displaying F23) or heats only the upstairs radiators but doesn't get very hot. Until recently I was able to get some heat to the downstairs radiators by turning all the upstairs ones off, but now the downstairs radiators don't come on at all and even the upstairs ones aren't all coming on, and when they do they're not getting very hot. Been advised it could be the pump?? Don't know if it's relevant or a coincidence but I did not have my heating on for 3 months through the summer, something which I've never done before, and it is since then that the heating will not come on properly. Would really appreciate any advice and/or recommendations of/offers from heating engineers. It's not urgent as I'm managing with convector heateEd but I'd like it sorted soon as possible.

Many thanks in advance

Check the system is at the correct pressure and that all the radiators are properly bled of air.

If it's neither of those you'll need to get a heating engineer in to inspect the boiler.

Hi there, thanks for the reply. Yes done both of those things, not helped I'm thinking I will definitely need a heating engineer, just don't know where to start in getting a reliable one that knows what they're doing and won't rip me off. I'm not saying I'm likely to get ripped off before I offend any heating engineers out there!! But unfortunately after previously been the victim of an unscrupulous tradesman I am a bit paranoid now ? I've now seen another thread on here with some recommendations on engineers so I'll look there but it may be a bit out of date, so I'd still be grateful for any recommendations. Cheers ?