DirectAxis taking monies over and above what is owed

So I have (had) a DirectAxis loan via Wesbank Now my Monthly installments were R1634.91. Last month I had R829.63 Outstanding of which I was R556.36 in advance so I was only in reality R273.27 was left to be paid add to that the R320.00 "protection" (******ion) plan and the R115.00 Levies and the amount due would be R708.27 add to that the interest due (I don't have access to their arcane formula) my due amount would be no more than R1000 yet they Still deduct the R1634.91 Why is this? Why even charge protection? This is the final installment. So in reality my due amount would and should be sub R500. So DirectAxis is taking money that does not belong to them, now the Oxford Dictionary defines *****ing as such: Definition of ***** - take (another person's property) without permission or legal right. So they are *****ing my money, I want it back plain and simple