As has been mentioned, you didn't have a contract with or employ the engineer yourself,
so if you have any comeback at all, shouldn't your claim be against the SELLER,
for selling you a machine that is "not as advertised" ?
Any issue with the mechanic and his inspection / service would then be one for the seller that employed him ?
Oh, and with regards to :
the CAA have instigated a MOR (so they don`t believe it either
For your own sake, and so as not jeopardise your situation, I would be very careful about publicly stating what someone else - i.e. the CAA,
believes or doesn't believe - that is for
them to state - when they publish the result of any investigation, not for you !
CAP382 :
The objective of the MOR Scheme is to contribute to the improvement of flight
safety by ensuring that relevant information on safety is reported, collected, stored,
protected and disseminated. The sole objective of occurrence reporting is the
prevention of accidents and incidents and not to attribute blame or liability.