Puente Hills Nissan They are trying to charge me an extra 400 claiming it as a deferred down payment. Industry, California

I purchased a 2012 Nissan Sentra and I paid 1250.00 in down payments, I also gave them 2003 Lincoln Navigator as a trade in. I had to resign the contract for the car three times come to find out it was because they were overvaluing the car and telling the bank that it was worth $25797.06 when it was really worth $17379.81 meanwhile they were telling me it was my fault because my credit was so bad and I didn't want a co signer on the agreement. Then with the last contract I signed I was told that there was a optional $400 extra that I needed to pay if I wanted to keep the alarm system in the car. I at first told Joey finance manager that I didn't need it because to me that was a lot of money to pay for stock alarm it doesn't open the trunk it just opens the doors. He told me he would give me time to think about it. I got my first statement from the bank and I made my first car payment I called them and asked the bank what was covered on their financing and why they didn't cover the alarm they told me they did finance the alarm I then told them what I was told about the alarm and they told me that I owed the $400 to the bank and not the dealership.Who in their right mind is going to pay $800 for a alarm system? I then called the dealership to clear all this up and offer to take the car in to have the alarm removed and they refused saying I need to pay it or go to court on it. I have my old contracts to prove that they are trying to steal extra money that doesn't belong to them. I have since reported them to BBB and got a response saying this Company's Initial Response - Posted 01/31/2012

The alarm you purchased was financed through the bank and the deferred downpayment of $400 is due us as the bank only financed the the total sale amount minus the trade in value and the downpayments which are due us the dealership. Out of courtesy, we will waive the downpayment of $400 but we need you to come back in, so we can remove the alarm that has been pre-installed. Our collections manager will be in touch with you to arrange this. Thank you. Out of courtesy, we will waive the downpayment of $400 but we need you to come back in, so we can remove the alarm that has been pre-installed. So now I will still be paying $400 for an alarm that I wont have anymore in the car even though they got their money for it from the bank already What the hell isn't this illegal? I am not the only one they are pulling this scam with I have another person who can tell you about the same thing happening to them and now that I am googling about it there are also several reviews claiming the same thing happening to them or something similar.