Chapman BMW on Camelback

I leased a brand new BMW 328i with the dealership agreeing to buy-out the last payment of my lease ending on my previous car. They were anxious to have me take delivery the same day as our agreement, but I told them I couldn't until two days later. So, two days later, I then picked up the car, signed the papers and paid the agreed fees. Less than 24 hrs. after taking delivery of the car, the dealership's finance office called me and said that they no longer wanted my trade-in car as the buy-out for the car was different than they told me. Within an hour of their phone call, I called them and told them I was on my way back with the car and would take back my trade. Despite this, when I arrived, they didn't have the car. It was a few blocks away at their used car location. The dealership failed to do their due diligence at checking out the correct buy-out figures on my trade and told me because of it, I would owe them $3-5000 more. Moreover, they had an additional two days to do so. They seemed genuinely surprised that I brought the new car back to them, and I got the impression that they wanted me to get attached to the new car and would be willing to pay them whatever extra they wanted. This situation, unprecedented to me in owning dozens of cars, was through no fault of my own. I have both a top credit rating and reputation, and I was appalled at the reprehensible way they did business with me, a new enthusiastic customer to their dealership , much less ANY customer. The sales manger really had no excuses nor offered any admission of a mistake on their part nor offered any apologies. I discourage anyone from doing business with this dealership, who at best was incompetent, and at worst deliberately deceitful.