Worst after sales Company ever

A leak was noticed on the heat exchange on my Warmflow boiler in June 2021. The boiler was installed in October 2017 which made the heat exchange parts warranty of 5 years still valid. The problem was found to be a leaking gasket which was held in place by a cover plate and two 6ml stainless steel studs and nuts. My boiler technician who has serviced the boiler annually from new attempted to undo the nuts to release the gasket useing a small spanner with little or no pressure resulting in one of the studs shearing off. He contacted the rep who said they would find someone to weld the stud back on, but this did not materialize and I was offered a new heat exchange at the cost of £175 through my technician, who was also offered a free Warmflow boiler flue to induce me to accept the offer, which he refused. I was contacted by Warmflow who suggested that the nuts had not been undone on a regular basis when serviced NOT TRUE. The next excuse was, had the nuts been taken off one had been refitted on a cross thread, ONCE AGAIN NOT TRUE. I still have the nut and stud as proof. Their Customer and Care Manager who came up with these excuses must be telepathic as no one from Warmflow has even bothered looking at the boiler or requesting photographs. I have however had 6 people view the problem including myself, and all agree that the sheared stud should have been at least 8/10ml thick as the original stud of 6ml outer thread was totally inadequate for purpose. I have had a new boiler installed, obviously not a Warmflow and I am totally disgusted with the unprofessional after sales policy of this Company. Anyone reading this review please don't be under any illusions that your Warmflow guarantee is genuine as I've found it's not worth the paper it's written on