On 17/05/2019 21:43, Vir Campestris wrote:
In 2010 my mother replaced her gas boiler. Old cast iron lump with
vertical flue with a Glow Worm. Supplied by British Gas. Even though I
told her not to...

It's gone wrong, and the guy looking at it reckons it's had it. That's a
surprise to me... is it likely, or is he another cowboy?

Assuming it isn't repairable, what's the current view on boiler
manufacturers?

Why do you assume that? Most gas fitters, or their wives/partners, make
more money by dismantling and selling the bits. It's a very buoyant
market created by so many being persuaded to get a new boiler when the
old one just needs a new part.

Find out what's wrong and use ebay!