Is the dealership I brought a used car from ripping me off? what should I do?

I just brought a used 2002 Cadillac Seville SLS from a used auto dealership (Greenway Motors to be exact). The car is about 11000 plus taxes, doc fees, etc.I put $1500 plus a trade in value of $1500 for my car. $3000 all together for the down payment. They said many banks rejected me because of my credit but one bank approved me for a 36 month financing.

They told me since I came in when they just got the car, it wasn't ready yet. So they said give it 2 days and they'll be done with detailing the car. I signed the contract for the car, gave them the money, & drove off in MY own car (which wasn't traded in until i receive my cadillac).

The day i come to pick up the car they said it's still being detailed, the parts came in late. So they said call the next day. When I called the next day all of sudden the guy who sold the car to me (Mikey), tells me that the bank is now NOT trying to approve me anymore because of my credit and they want a car for me with a lesser amount. He said he's trying his best to fight it for me because he wants me to get the car and he's negotiating with them so basically I'd just have to wait. I already switched my insurance over to the new damn cadillac like they wanted me to in order to take the car off the lot, I signed the papers, but I STILL don't have the car and today is the fourth day! WHAT'S GOING ON? Are they ripping me off? Or does this actually happen? I've never had anything like this happen before, why would a bank reject me after approving me? Someone help please, I need answers. I'm going to the dealership tomorrow and will most likely end up requesting for my money back. I'm PISSED.

THANK YOU IN ADVANCE