Revolving loan

I took a loan from standard bank and paid it off. To my suprise they are still billing me and their statements have discrepancies. I have tried contacting with this regard but they are taking me from pillar to post. No one is giving me a straight answer in regards to these statements. They call me almost every day about payments and yet i am still waiting for a report from their investigations. Kindly assist in pushing them to provide me with the correct statements as they can't assist me even after i provided them with the loan contract as they have requested.