Unhelpful bank

I app**** for vehicle finance online online and was pre approved pending validation. I then went to the dealer because I needed to change the vehicle details. They later declined because of no credit lines. When I spoke to them they said it was all right because I have no credit, and nobody wants to give me credit if I havd no credit. All the other banks said I should go to the bank I use, which I did. I even opened a credit card which I am paying very well. This is not helping at all, and I need the car, and they have access to my banking profile and proof that I can afford to buy the car. I am tempted to leave FNB because they are not helpful at all. I have been calling whole day given different numbers and still no help. Soooo disappointed.