There are a plenty of dealerships out there that will pull shady things like that on people. I for one learned the hard way on that case. Went in, first time buying a vehicle from a dealership and on my own at that. and needless to say they hosed me in every possible way they could. I ended up taking a hit on that vehicle and had problem after problem after problem with it. Made enough payments to get it under what it was worth and traded that and my other vehicle i had at the time and bought me my amazing sonic i have now!
My screwjob i got from buying that one vehicle taught me what i needed to do and prepare myself for, for when i went in to buy my sonic. Nothing got past me this time around. i made sure everything checked out, the amounts were correct and what we agreed on and so on. I was and am very happy with my purchase of my sonic. It sucks what happend to you. but its a lessoned learned and now have that for knowledge of the next time you go out buying for a vehicle.