What do motor mounts have to do with the engine's wiring harness?
A damaged wiring harness must be replaced:
it won't fix itself,
its unreliability makes the car dangerous to drive,
the constant aggravation will drive you nuts,
the car can't be sold this way - even if you bought it so.
The pain can be lessened by installing the new harness yourself -
tedious, dirty and time consuming but no physically hard wrench pulling.
MB, stop thinking the mechanic is dishonest for IMHO you are being
dishonest, with yourself - about the lousy car that YOU bought!
Remember, nobody forced you to buy THIS car. You thought it was a
bargain - that's the worst kind of luxury car to buy, there are no bargains.
One pays up front for quality or later for having bought crap, but in
either case one pays!