I have two reservations..one at enterprise, one at dollar. We have a convertable booked at both. We really want the mustang that enterprise offers and not the chrysler that dollar offers. Dollar is $50 dollars cheaper but I'm not worried about that. I have a credit card but its only a $500 limit credit card that I basically use to rent cars. I have horrible luck when it comes to rental cars. Last year when I tried to rent from Thrifty they put in the wrong address and my card got rejected and they would not run the card again with the right address. Ended up renting from firefly as they honored the price I had booked with Thrifty. I also had a problem with fox rental when they changed their policy and charged a large deposit. So now I double, triple check the policy and really like the idea of having a backup reservation. I have the blue chip from dollar rental. If I go with enterprise and choose not to use the rental with dollar will I still get charged? I know enterprise will not because they don't have my credit card info. So if I go with dollar first, I'm ok, but thats not really the car I want. I really want to use enterprise, but I have never rented from them in vegas only have used them when I have had a car accident that wasn't my fault. (insurance claim) I am nervous about cancelling dollar and only having one rental car available or not cancelling dollar and they charge me. So major question is if I dont cancel them until the day I arrive, will they charge me?