I can sympathize with your frustration, but it sounds like your car was on the cusp of all sorts of trouble when you left it with FlightCar.

I don't know their policies, but if I was the person renting your car - I would have been extremely frustrated that FlightCar even accepted your vehicle into their renting pool.

I do hope it all works out well for you though - and your story has successfully discouraged me from leaving my car with any such service.