When renting a car in the US, you've got to be very alert and have to carefully read the contract and everyting they ask you to accept or inititial.

I had cases where the agent told me that certain insurance options were already included in my voucher and I only had to hit accept on the little touch screen to activate the coverage. I noticed that they were listed with a price per day though, so I could ask the agent to take them back off. At first she told me this wasn't possible, but after a longer argument ended up doing it.

Another trick they use is to tell you that something is only USD 5.99, but neglect to mention that this is the price per day. Multiply it by 21 for a three week rental and you'll arrive at a completely different amount.

No matter how tired you are, you've got to read before you sign.