Help with car dealerships.?

Recently I have traded my 09 Honda Civic in for something better in the snow. I went to the local Subaru dealer here in my town. I walked off with an 03 Subaru Outback and some extra cash. I drove the car for a day and the check engine light came on. I took it to Autozone so they could run a diagnostic test on it. They said it was the catalytic converter. I immediately went back to the dealership and told them what happened and I was not happy with the car. I wound up walking out again with an 05 Subaru Legacy and no extra money. I bought the car on Monday and now on Friday I go to use my horn and discover that I have no car horn. Now I'm extremely unhappy that they first sold me a car with a bad catalytic converter and now they sold me a car without a orking car horn. I really just want my old faithful car back now. I live in Boulder County, Colorado does anybody know what I might be able to do?