[joeysteele]

It's down to you, is he good at his job when he does it, has he damaged the car,do you mind him having that car or not for the job required,whe he is working.

He has probably overstepped the mark from what you say and disobeyed your instructions.
In the end,is he worth other chances or not, only you know his work record,so if he has value, you could try to work something out, if not, you are left with one course of action.