Try A&P Gas 8802 6969.
You could also ask the Real Appliances shop in Crouch End, though I don't know if they do gas as well as electric appliances.
This link here from a couple of years ago has a few recommendations for local people.
I put a message on your page.
I would try Lisa she sorted our boiler out before Christmas.
how do I contact Lisa? claire: no sign of your message? I replied that I bought my Beko gas cooker from Real just 3 years ago but they no longer do gas repairs Beko can only offer a year's agreement of over a hundred grateful for help SM