Were you happy with your choice of boiler engineer in the first place? British gas may feel like the BBC of boilers, sort of, but I think they would probably be more expensive than a local engineer. There's nothing to stop you shopping around for a boiler yourself and pay for it to be installed. I know nothing about boilers I should add. PS They do have a lifespan and if it's quite old it may be worthwhile to replace it than repair it, it that were possible.