Horror story from my youth. I was a novice mechanic, mostly doing simple R&R stuff and basic fluid services, brake jobs, sweeping, etc. I was working in a smallish shop (6 bays) that specialized in British cars but took in other Euro vehicles from time to time as well. The owner was a cranky old Brit who knew everything about those cars.
We were shorthanded when one of the more experienced guys went on a local unplanned "vacation" (aka county jail), so I sort of inherited his toolbox and started getting more interesting work.
So it's the early 1980s. One day a local rich lady rolls in with her perfect yellow Xj6 that had very recently come off the short Jag warranty. Boss greets her next to where I am working on a Jensen Healey starter. "Engine is making a weird knock/clunck sound" she says. The boss pops the hood, revs it a couple times, drops the hood, looks around and says, "hmm This could take a while..." He asks me to give her a ride back to her place and diagnose it and he tells her we'll bring it to her when it is fixed. She seems happy enough about that. So excuse myself to go clean up a bit and get in the passenger seat. "Don't you want to drive?" she asked. I told her no because I wanted to focus on what I could hear and feel and let her worry about traffic. We set out and she immediately puts the radio on. I asked her to turn it off. (No this isn't gonna turn into a penthouse letter to the editor...) Anyway, it's definitely "Something" but the car seems to be running ok. I drop her at her place and drive away a couple blocks and then pull over, and pop the hood. I rev the engine. It's a loose alternator bracket... The belt is staying on but the alternator clunks back and forth as you get in and out of the throttle. I didn't bring tools so I just drove back to the shop.
I tell the boss about my diagnosis and he says, "You aren't qualified to diagnose Jaguars. Move the Jensen, we have time on that. Bring in her XJ, pull the valve cover off. I think the problem is in the valve train." I felt like an idiot - how could I have missed it?
So I snug up the alternator after checking the belt was still serviceable. I put the batt on a charger figuring the alternator hadn't been making current all that well.
And I pulled the valve cover, as instructed, and told the boss.
He makes me wait, says "go back to the car - wait there... check her tire pressures and fluids etc. because he has to make a call. He calls someone in his office, while looking at me and the Jag through the window. I don't know what the heck is going on... but it's ... weird.
He gets off the phone and walks over to my bay, smiling. He goes to my (borrowed) toolbox and rifles through a couple drawers till he finds the one with the hammers and mallets. I think it was a 2.5lb ballpein that he picked up. He looks right at me and says something like, "you're a smart lad, you know the story Robin Hood I'm sure." And then he beats the #$%* out of the front end of her valve train with 4 or 5 blows from the hammer. "She's rich, we're not. So fix that horrible engine problem she clearly has and she'll be a happy customer... And keep your mouth shut."
I was in shock. Didn't know what to do or say. I think I must have just stared at him. He walked off and one of the other mechanics just said, "he does this once in a while... when he has some tax bill or whatever. Don't worry about, don't say anything. Trust me on this - or he will throw you out and give you a bad reference if anyone calls. Just, fix it.. It'll be fine. If he makes out on the deal, he'll kick you back a hundred or so. Maybe."
So it was ugly on ugly. I needed the job, I was finally get to do real wrenching and not just boring oil changes, and here I was helping him steal.
I felt sick about it and had started looking for another gig the day it happened. But I did the work, and it came out well, and he told her she was "lucky" and "smart" she came in when she did - what if the engine had seized up when she was on the freeway or something! Or at night! She could have been in a dangerous situation. He billed her a lot - like $1500 maybe which in 1982 was A LOT of money - and she was happy and grateful. She even hugged me, and to this day I feel bad that I didn't say anything.
He offered me $50. I said, "no thanks, I made an agreement for a wage and that's fair and enough" or something like that.
A week later I found another gig. I quit... got my stuff and left on good terms (told him I was going back to college).
I called the police to tell them what he was doing, they said to call the better business bureau and some agency that reviews and regulates garages. No one wanted to believe me or do anything about it... I had no photos, no written evidence, nothing to prove what I saw. The head he damaged was long gone. I haven't really trusted a shop since.