Capitec the ***** bank

Well I took out a personal loan of 165000 in May this year of which 4707.12 is being deducted monthly. Last month my statement said it was now 152000. This morning after the deduction the amount went up to 159000 of which I don’t understand how that could be. I’ve never missed a payment nor have I ever reversed one. Fast forward I call the center and the lady helping me says they added interest last month. And this is not the first time money is being deducted and then not reflecting on the actual account. If they have been deducting 4707 for five months now the amount should be less than the one I’m seeing on the statement. I didn’t do accounting but I know basic math.