Well, some things happen to us that can make us lose control of our anger; bringing my car for you to repair with no physical damage and then coming back to see such damage can make me arrest you, but the reason given by the mechanic was considerable.
In my own opinion, the mechanic should take full charge of the damage when the man pays for what he wants to repair before the damage, but if there's any negotiation and agreement between them, then it should be 50/50, Since it wasn't really the mechanic's fault, life is hard.
Thanks for your contribution.