Do shops still sabotage cars for profit?

I had a customer of mine take her benz to a tire shop for tires.

By the time she was ready to pay and go, the shop owner told her that she needed front brake pads/rotors, front and rear shocks, a steering dampener shock, and now the check engine light is on and the car is runniong rough.

She called me and was furious that her car was messed up so she picked my brain.

I told her I just put front brakes on it 2 months ago and no way she would need them.
Her shocks were fine as well as the steering shock.

I know she needed motor mounts but that was not her problem so she had me talk to the shop manager on the speaker phone and I was trying to help him diagnose the car and he told me I did not know what I was talking about.

I told her to get her car out of there and I would make time today, new years eve, to look at it.

Well, tonight I find that she needed spark plugs and wires, and I found misfires on cyllinder #3 only.

I remember the guy from the shop telling me the misfire was on cyllinder #4 only so upon removal of the spark plug wires I found that he had cut the insulation of both #4 wires to the core wire.

She said he messed with the car after it was running bad the other day and she did not know what he did but it was better but still stumbling after he messed with it again.
I think he pulled a couple wire away, then popped them back on after she raised hell.

Yes I replaced her much needed spark plugs and wires but he obviously cut the #4 wires because they were clean razor cuts and I've never seen them break like that, and all the other wires were perfect looking.

Long story short, I got her car running smooth as glass for $300 less than what that idiot was going to charge her and I used factory Mercedes parts too like I always do.

I explained everything I found to her and she is going to go lesbian, Bruce Lee on his Asian *** on Monday she says.... LOL.

I did not think there were still idiots pulling this kind of crap out there now days.
I can't explain how they think this kind of crap is going to HELP their reputation.

I feel like going in there and choking that asswipe for messing with her like that.