Rejected Application

I am an FNB Platinum cheque account holder who also have a bond and personal loan with FNB. I app**** for car finance with Wesbank thru Audi Fourways and my application was rejected. called call centre and i got told that its because my Trans Union score is 805 instead of 850 required. I fail to understand that a bank i bank and loyal with will deny me a car finance based on that. I need to buy a car and i know i afford. My accounts are all up to date as per trans union report but still i dont get the car finance. I feel grieved because as a customer of Wesbank/FNB i believe they should have approved my application. FNB has been the best for me, they approved my bond and i pay it well but all of a sudden i cant afford a car of R170000 when i have a bond of so much money? This is really unfair and i feel I have not been treated like a customer.