I booked a prepaid rate from Hertz with Amex Plat CDP (211762) 2 months ago for a rental in mid-November. However, due to some reasons I need to cancel my Amex card before rental period.

What do you think will happen at rental location? Do they ask for the card physically there or is it enough that I have used the CDP and paid with Amex? This is my first rental using Amex CDP so don't know if the agents really request a card for proof or not..

What is the worst case scenario - they ask for card and I don't have it.. to pay the difference (-20%) with Amex?