Payment on loan

This is totally ridiculous, stupidity and incompetency. During March NedbankPersonal Loans has now deducted 3 x money from my bank account for payments on my personal loan after I have paid the arranged amount on the 1st of the month. A new arrangement for the next 4 months has also been put into place . Then the first amount was taken with an overnight transaction, amount R 8190,00. After a call to the bank and many minutes on the line, the amount was refunded. Another new arrangement was put into place. Then another overnight transaction on the 11th for the amount of R809.00 went off. Again a call to the bank with promises of a refund.apparently on the system the arrangement of the previous week was not found! Then the following night another overnight transaction of R323.80 went off . Leaving my bank account in a low balance! What is happening and what do one call this ----- definitely bad customer service. And how does Nedbank allow amounts to be taken from your bank account without permission ? Do I have to pay 4 payments in one month? Really? And spend hours on the phone to try and sort it?