His father got it done probably and he's just telling his story here. I'm sure he didn't commision the work himself, he didn't make that decision. Non-technical folks are easily tricked by these haramkhor mechanics. The mechanic probably sweet talked them into getting it done to such an extent, that they themselves believed the motor was dying. Hell I was once sweet talked into getting my oil changed so bad. Despite me knowing it wasn't necessary at all I had it done. Anyway he's a kid, he will make mistakes and if smart enough, will learn from them.
So point out the discrepencies. Faulty work done once can be corrected you know.
Anyways I told it like I saw it. No harm intended.