Capitec ripping people off

I have been banking with Capitec Bank for more than 10 years now and took a personal loan with them.'' The loan was 74 000 for 57 months (5 years) I was supposed to finish my installment by end of October 2017 and they are telling me I still have another three and a half years to pay, I have been paying this loan since 2013. I used to pay 2400 and then asked them to change it to 1800 with 600 difference. Then Capitec Bank extended my installments by three and a half years, so in total I will be paying capitec bank for 96 months. which is not in our contract. I have requested them to help me several times and all they do is take me from one Consultant to the other. It is obvious that I am being overcharged and this is negatively impacting on my credit records and limits the chances of me moving forward financially.