Not getting what i payed for at the car dealership?

I recently bought a new Toyota car from a dealership. I wanted some type of security for my car so I asked them if the car came with any basic type of anti-theft system (ie. gl breakage senor, engine immobilizing system). Of course they lied (car had an engine immobilizing system) and said the car came with nothing. I asked them give me a security system for the car and they charged me $500 for it. After all paper work is done and signed, I call in their parts service to schedule an appointment to have the security system installed. Then, I find out from the parts service guy that the security system they are going to install isn't even a genuine Toyota system. It's some crappy aftermarket system that I've never heard of. I told them that I thought it was going to be an OEM Toyota security system like the ones they had in the brochure, but they told me no and said theres no refund or exchanges because I've already signed the paper. What can I do? Is this fraud? False advertisement?