Mopar Dealer Service Department - Am I Correct To Be Pissed Off???

1) The reason you were not charged the $185 is because they never planned to look into/diagnose anything. 99.999% of the time, any charges for time spent diagnosing will appear on the bill. IMHO, that is precisely why you were told the $185 would be taken off your bill.
2) In 1988, I bought a 1988 Chrysler LeBaron Convertible. 2.2 Turbo engine, red with grey leather interior, PW, PB, PS, A/C, loaded. I loved that car. Shortly after the bumper to bumper warranty expired, the left rear quarter window stopped working. The motor whirred, but no movement. I looked at it, and the round ball/tip had come off the cable. The dealer wanted about $250 for the entire assembly (probably about $900 in today's dollars). So I pulled the whole assembly, jury rigged a tip on the end of the cable with spare stuff laying around in my garage. It worked for the next years.