I currently have two reservations for our November trip - one with budget and one with national. I seem to remember that when booking through the Emerald Aisle site it said something about you must cancel with 24 hours notice or you'll be charged a day. Since they have all my credit card info, I just assumed this would happen. My budget reservation is about $25 cheaper, but I've never used them before and would like to hang onto the National reservation in case the budget doesn't go well. I'd also like to hedge my best with the possible car shortage. SO back to the original question, ever been charged for a car rental that you either didn't who up for, or canceled after your expected rental time?