Didn´t get the car I rented!! Very bad!

I rented a Jeep Grand Cherokee and ended up getting a GMC Terrain and didn´t get the baby seats I requested. At the counter I was not informed that I was getting a different car. It was only when I got to the garage to pick up the vehicle that I was told to choose any of the cars (in the same category) that were parked there... I was a bit shocked. First I chose a Pathfinder that suited me very well but after putting all our luggage in and starting the car a message came up on the panel ¨key - low battery¨.... went to the company booth and was told they didn´t have a replacement battery so I had to choose another car. What a nightmare. I then chose the Terrain a which had less space then what I needed. The car was good and clean but space was crutial in our trip and the overall experiance with Dollar was bad.