My rate jumped from $150 to $650, and just assumed it was typical Hertz IT error with the website.
I selected a PC car and of course the $650 rate printed at the gate. The gate agent couldn't fix the rate so I had to back out and go back to the office, and 15 minutes later a manager helped the agent hand key the rate with the original rate. What a royal PITA.
This was a AAA rate and they manually adjusted the daily and hourly rates. For the Amex Plat CDP I suspect that might be harder for them to correct the 4 extra hours.