standard bank loan. bad service. paid the full loan amount but they say i still havent paid in full

I took out a revolving loan in 2013 for R25 900 repayable in 48 months at R859.02 a month. I have approached them from time to time after 48 months. I was informed that after +- 20 months R3800 would become available for me to use. what the bank never discussed with me was that if i transfer that amount to my cheque account whatever money i have paid comes to nil. I now had to start from afresh. After 144 months paying the bank R859.00 I still owe the bank R21 832. I'm confused and cant understand why the bank is still debiting my account up to today which is gone 12 years now. When i approach the bank I receive no feedback from them. I feel cheated and my whole life have banked with STANDARD BANK but now I have lost faith in your company. I hope to receive some feedback and my loan closed.