I want to know if I have a case and is it worth it?

I agreed to pay a down payment of $1075. When I went to the dealer they changed it to $1500. I told them I have only the amount I have, they continued to speak to each other and said they will put down that I paid the whole $1500 in cash. I was confused and thought this how they handle their business. I paid what I agreed to plus a 3% fee which I wasnt aware of until I pulled out my debit card and they informed me so in total I paid $1112.63. I couldn't leave that day with the car because I drove to the dealership on my own. I came back 2 weeks to pick up the car and gave them a text as a heads up. Now at home and getting ready to make moves and check a mechanic and register the car I noticed they didn't put the paperwork in the car like they told me they would. So I have the car but cant register it without the documents. I asked them to send it over and they told me not until i pay the rest of the down payment that I didn't agree to.