check how much u own the bank.
Normally the dealer will tell u he settle everything for u, including the bank loan, then pass the balance to u. /and the best thing is the bank never sent the settle statement to u. so the dealer normally will just add 300 to 500 to the amount, without u knowing. and people just too lazy to check with the bank, and the dealer got off with extra $500.

when one finds out, the dealer will normally say, oh it is a mistake on their part, soorrry hor, we will refund u.

and so no one report this type of cheating to the police and it continue.
good luck to your sale.