Linking car rental reservation? Alamo

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?

 

I would suggest that you call Alamo and ask the question. Give them your reservation number and have the agent recalculate the cost for an additional day to be added on. The rate for the additional day may be higher than your reserved rate, but maybe not as high as a separate one day rental. Or if higher not high enough for you to undergo the hassle of returning a car and getting another one.