Live and learn. Did the tech at least give you the old parts back as well?
Before you fix this guy's botched job, take some detailed photos of it, so if he does try to get payment from you, you have a record of each and every way he screwed up your guitar. Maybe post them here as well so we can all have bulgy eyes at it. ... and maybe a good chuckle when it's all fixed.
Once you have successfully done the work yourself, you will no longer fear getting into the guitar wiring again.
And remember that you can always consult with us if you have any problems.