No cash back as dissatisfied or cashback was given,n ,now I'm paying aoo much

I bought my second car with a shortfall, I asked the guy for a cash back that was advertised on the atm zen which not when looking at my documents it was not included or the dealership assistance. I told this car I rent to them because the other dealership offered me another car when I wanted an amt zen,I wish I went there cause of tge cas back. But this one iin centurion mall he didn't includ cash back or dealership assistance mind you I got that from my first car in a another dealership but centurion didn't now I'm paying soo much.