16% interest rate charged on 2nd hand vehicle

I have app**** for vehicle finance about six months ago and was approved by Wesbank with an interest rate of 16%. Not knowing much about vehicle finance I accepted same. I have been going through Google and researched the interest rates on vehicle finance and realized as a citizen of South Africa, the interest should have been prime plus 2% maximum. Further investigations have revealed that other clients have been penalized as I have, and their accounts have subsequently been adjusted. I would appreciate if somebody from Wesbank could urgently contact me in order to attend to the said matter.