Incorrectly diagnosed the issue in my heating system causing me to throw away a perfectly good therm

Incorrectly diagnosed the issue in my heating system causing me to throw away a perfectly good thermostat and replace the system. There was nothing wrong with it; there was just a faulty piece of wire that he didn't check. When I bought this to his attention he told me he was just a "boiler engineer" as if thermostats have absolutely nothing to do with boilers. Refused to engage with any kind of liability and blamed me for the situation despite having followed his advice.

29/11/2023