It seems like every time I rent a car, I end up getting a different car when I arrive because they gave my car away. Sometimes they even try to up sale me like, "sir, we actually don't have any midsize available at the moment but we could upgrade you to the full size for only $17 more dollars a day. Or you could get a smaller car for no extra charge". Huh? I reserved a midsize car -- why did you give it to someone else? Why in the world do I have to pay more for a bigger car when its your fault that my car isn't here. Okay, I will take the smaller car I guess. Here is the cash I owe you. Oh, you don't take real money here? Well, how about I don't rent a car at all. Thanks for nothing.
Here is one of my favorite Seinfeld scenes ever that addresses this injustice. You should spend the 3 minutes to watch it.