Builder did illegal gaswork, possibly a riddor, and you think he is quite cool.Prove one word of that post you have just made
You had a boiler installed illegally.
Together, that makes you engaging repeatedly in dodgy gas work.
Now that was really simple.
Don't even try that on me I know more about RIDDOR than you ever will, I was the safety manager for my company for more years than you have brain cells, report this issue, **** off.