Vroom complaint: CONTRACT

My name is Bradley and I purchased a 2019 Ford f-150 4×4 from VROOM online in Stafford, Texas. I traded in my 2019 Ford F-150 simply cause I was needing 4 wheel drive. They picked up my trade in within 5 days before deal was even done. First of all I sent them $4000.00 dollars for a down payment which they excepted and deposited quickly. It took about a week to get all documentation finalized and signed by myself and vroom. Registration was also put into my name. I have all finalized documentation. I tried making my first payment in November and it was sent back to me, so I was like what now what? I finally got a hold of someone their and they tell me that they hadn’t completed my documentation and I would have to apply all over and also send them another $1000.00. I told the lady that she was crazy simply cause I have everything stating it was a done deal. I even have e-mails stating it was final. So now they want to get the truck back after having it for over four months and then they will give me my down payment. I have no problem giving the truck back, but I want my deposit back first. I know once they pick the truck up I will never hear again from them. After everything Vroom has put me through, I only think its fair to give me my down payment back before they pick my truck up… If I have to I will go public with this. I’m not that kind of person, but I think its un-fair the way they have treated me.