The Hertz deal simply doesn't work. I tried, failed, and called both Hertz and amex and wrote emails etc. Nobody could fix it. There are too many rental car companies for me to put up with this kind of BS. Plus, on one of my last trips to LAX, the rental process was lousy and the car choice was horrendous.
The time after that I rented from Sixt and got a brand new Camaro convertible for only a few bucks more than some econobox from Hertz. I got Sixt platinum status through Club Carlson which I got through my Amex. Works well.