First off, I have no relation to Manchovie. I've never talked to him before further than replying to one of his posts on the forums.
It honestly sounds like you're one of those "nightmare" customers. Gundoctors are few and far between. Some of them have ALOT of work to do, and as far as I know there isn't anyone in the country who has a 100% full time job as an airsoft gun doctor.
When someone is doing something for you, don't text them and keep calling them for updates... I know when people do that to me it drives me nuts.
You should always try the gun at the tech's place with BB's... I have a huge bag of BB's available, and 90% of the people that pick stuff up at my place shoot their upgraded gun and have the option to run it through the chrono if they want to.
I can't comment on the gun not working as I have never (to my knowledge) seen or heard anything about his work. It sounds like something that could have been sorted out much smoother if both parties had remained polite and civil.