Most Transo engineers dont have the ticket to work on boilers either so he probs just had a quick look, i dont like BG but saying the engineer must be wrong because so and so said it was ok before and so did transco is utter rubbish!
I agree. The fact is, BG or not that boiler set off alarm bells. Not liking BG whether wanting a sale or whatever would leave that on. They are still under the same noose. OP is shifty at the 4k price and wanting a fix. Never trust a customer.