Quite a few years ago, my wife went to purchase a used Mustang, naturally I went along, we found the car she wanted, at a fair price we could afford,
I told them there was a power steering leak, they fixed it (New pressure hose, a ten buck part) and the next day we drove it home.
Mind you She (At the time) was a bookkeeper for a major bank and as an employee had the financing approved beforehand, so all we had to do was find a suitable car and drive away.
Yup you guessed it, a few days later the dealership called and tried to pull the "Financing is not Approved" scam on us, I just laughed at them and hung up.
They tried repeatedly to get us back, and each time they called I just laughed at them louder and louder.
Finally a cop called and told me that "We had Stolen the Car".
I told him exactly what was really going on, and he was quite pissed that they had tried to use the cops in a scam. He said "I'll take care of this" and hung up.
Shortly the dealership was Calling to tell me "A mistake had been made (Mind you we had been paying the bank for 4 months at this point) and I told them "Yes, and you made it".
End result the dealership closed, the salesman and finance guy went to Jail, and we never heard from hem again.
So the Story Moral is "Have financing approved BEFORE YOU LOOK" and "When they try to call you back in, Call the cops and don't go back".