I am renting a car for my upcoming trip and got a great price for my four day trip. Then things changed and I added day on to my trip. When I checked the rates to add a day to the reservation the price more than doubled. Checking a single day rental, I was able to reserve the one additional day in the same class for $40 which saves me about $130 overall. Has anyone had any experience with getting them to link the reservations together so I don't have to go back to the airport and go through the process of switching cars?