NEDBANK incorrect dispute

I have been paying off a loan for years and years and years. Now Nedbank has put a flag against my name as a dispute and this has been recorded by the credit bureau. I cannot buy a car, I cannot do anything as this is reflecting NEGATIVE on my name. I have left numerous messages and asked to be called back. NEDBANK you should be ashamed of yourself. You are preventing a person who is paying you off every month from getting further in life.