Moritz of north Arlington Moritzbmw turned down us because we weren't born in the us arlington, Texas

Me and my wife were first time buyer,before we start looking for a car we checked our credit and score through a paid site.We went to the Moritz BMW in Arlington looking for  a preowned car range around 20k,we told the salesman how was our credit score and that we had never financed a car our credit was fair we even printed out the report,he ensured us that it will be no problem to get a car with low interest,so we picked up a car worth 27k.he took our application to marketing or sales dept after 10 mins came back to tell us that we we approved for the car with 5% interest!we tested drive the bmw and let us take the car at home because it was getting late,they ask us to come backthe next day to sign up the paper work that everything would be ready in morning we we very exciting to get a nice 2007 bmw for a first time buyer!!So next day everything went opposite!!! we got at the dealership  ready to sign the paper work,they told us that the manager is not around maybe we can come back later,we said OK they even filled the car with gas...i went to work that day,the phone rang i picked up the phn they started to ask me if i rent,how much we make  my wife and i,if we were legal resident or citizen,....i was so surprised to hear all that cuz they didn't ask these questions when we were there the day before,i was patient i answered all questions over the phone told them that we went to school here,graduated here been here more than 16yrs...after couple hours they called me back to let me know that we couldn't get the car because WE Are Not US Citizen!i was so shocked i tried to ask them if anybody who own a BMW is American citizen?They couldn't answer the question also they mention that we do not have car financing history,but we told them before we even filled the application that wasn't new!!The only new thing they told us is because we weren't born here!!!WE are not citizen we can't have the car.....I think the Moritz BMW cannot do business to anybody except us citizen!!!This is discrimination,.............