Nedbank personal loan complain

took a personal loan in October 2013, repayable in 12 months, sometime in 2014 the debit order was reduced without my authorization. then post that i was told my loan was in arrears and later was handed over to the collection department , but in september 2015 my balance was R 12 000 with an monthly installment of 1600 which based on the remaining life of 14 months would have meant that i was going to pay 22400 so even if the interest rate was 100% there is no way the loan was in arrears. then i asked for settlement amount which they gave to me , i settled mid september and followed all the instructions given to me, even faxing the supporting documents as requested but then end of september my account was debited with 1600 and upon following up , i was first told that the amount will be deposited back into my account within 7 days, which did not happen . after approximately 15 days i called again where the call centre lady promised to get back to me which she never did, three days later i called back again and again i was promised that they would call back and i made it clear that the last time they promised they did not deliver but again they did not call back.