What is the name of your state? California. I did a trade-in in Feb from local Kia dealer. 2 months later I received a bill from them for $450.00 with an overdue notice on it. The dealer informed me that they did not receive the full amount of pay-off from the car financer of the car I traded and I am responsible for paying the $450.00. Is this true? Do I legally have to pay them?