Cactus Jacks Lies to sell cars mesa, Arizona

We bought a car from here in febuary. The dealer lied to us in a big way. He said that if our paydays change for one we can change the payment due dates NOT TRUE. He also said they have a trade in guarantee that when and if we come back with the car we bought there when the balance was 2500 or less they will give us 500 credit and pay off the loan..This was also a lie. It is 1500 even though we have proof the salesman did say this and that he wrote it down on our paperwork. They said no its 1500 buy may be able to work with it if we come back in.  We have made all our payments and even a payment ahead and they are saying we are behind...WE have proof all the payments have been made. I have heard stories that more than one person has paid a car off and magically more money is owed. I should have known not to go there buy gave them the benefit of the doubt, boy did I learn a lesson. SO do not go to cactus jacks they will jack you around and lie just to sell a car oh and a hint they are not negotiable on there prices...there reason is well we dont know who will pay and who wont....thats the finance companies problem not yours oh wait you are the finace company their inhouse is called chicago lenders hmmm maybe thats why they lie to sell a car. We still have the car and still making the payments just trying to say buyer beware.