a complaint against Carmax

I bought a 2001 Taurus from Carmax in Kenosha. I brought it back the same day, after I picked up my daughter from school because the dashboard rattled, unbelievble. This is only the beginning. I have brought it back just about every month since. I have a history and its 10 pages long. Carmax refuses to give me an equal trade, even though, the used car manager told me to go on online and pick out a car for the same value as the original car, and he will "put me in it". The situation is changed. I have to use my old car as a trade in. There is something wrong. Carmax sold me a lemon, and they still want money for the amount of trouble I have gone through. Also, I asked Carmax to put me in a different car 6-7 months ago. They wouldn't do it.