unauthorised debit orders and added interest.

I have or had a loan at Capfin. I pay all my installments till the last debit order. I thought my account was payd and closed just to find them phoning me the next day to tell me that my account is in areas with round about R70 and that i should make a payment of R100(interest) before the day is done. I told them that i am unable to pay that amount and that i would pay it at the end of the month. They where so kind to send me a reference number to make the payment by then. After about 16days the 21st of the month i reserved a payment to go on a business trip and they debit ordered a full amount of R600. I reversed the amount just to mind them sending me R400 back the next day. This is very poor of the company after i have made a arrangement, and now i have to pay interest on that amount as well. And call them again to get a reference number. And for my luck today they are closed because of month end. And every day the interest get more and more. Terrible terrible company, they make the suffering just suffer more.