Re: my experince so far
This is just the thoughts of guy that's 'been around the block a couple of times'......
Judging by your post, it doesn't sound like you've had much luck with your 'mechanic'. Maybe you should try another one? Or, if you'd like to do more of the work yourself, you might consider going with an electric bike --- they seem to be a lot more user friendly for the less mechanically inclined. That should equal more riding/less tinkering.
Good luck in whichever path you decide to follow!!
You're never lost until you run outa gas.