So, some of you may recall a dealer told me i needed a new wiring harness on my Taurus SHO. (they also reflashed it without telling me killing the aftermarket tune, and making it run like garbage. I took it back to the selling dealer and raised a stink as it wasn't warrantied. They checked and said the harness wasn't shorting anywhere. however because it was running bad (due to running a 3bar map on a 2bar tune) they blamed the issues on a map sensor.

Get it home, Have my Father check it over for a week. He confirms the wiring harness is not the issue (no broken wires etc) said it was most likely squished when the engine trans had been removed in the past. (he's an ASE master tech). He also told me what was wrong with the car.

Finally took it to the best rated dealer within 100 miles. They also confirm the wiring harness isn't bad, and agree with what my father said was wrong with the car. (bad turbo sprayed oil into the Cats and ruined them)
They said the harness is CLEARLY not the issue.

So now im going back to the first dealer to get my Diag fee back, since two FORD dealers and an independent mechanic have agreed they were wrong. Any tips on how i go about doing this?