Finance charge issues

every month i pay my Credit card on time and just last week I resolved this credit life issue now I am noticing that I am being charged a finance charge of over R800 plus my installment of over R2000 now bare in mind I do not mind paying the installment due but the finance charge is a bit ridiculous why is this not included in the monthly installment yet I billed on 2 different amounts monthly. I called in last month and demanded a explanation now its been more than month and still nothing. Can someone at ABSA please explain because this is ridiculous. I am demanding my money back since last month and now its happening again.