Nedbank personal loan

Hello Peter I have a personal loan with Nedbank, on the day I apply for the loan they ask me on what day would I prefer for the monthly payment must go off so for logic reasons I said my salary gets paid in on the 25 so I would prefer payments to happen on the 27 of each month. On the first month payment went off on the 22st and did so every month ,due to my working conditions and were I work I could not contact Nedbak to ask why payments go off on the 22de so 5months gone past that payments go off on the 22de and this putt me every month into my overdraft. After months went past I finally were able to make contact with nedbank personal loan department and ask to change the debt order date for me to the 1st of every month so the did then on the next month day deducted double payments on the 27de and on the first of the following month so it is double payment on one month salary, So I took time off work to sort this out. So I phoned nedbank again and ask why they deducted my bank twice on one month salary they then said they will write the one installment back but it will take 5 working days after 5days the one payment was refunded but on the next month the debit order did not go off for what reason I did not know so I made sure that the money stayed in my account so that they can deduct it but they did not so I phoned nedbank again and they said I don't have to worry everything is sorted this all happend last year. This month nedbank sent me a SMS saying that payment will be deducted on the 27de but last night on the 25 of July 2019 a double payment gone off again. Nedbank never contacted me regarding behind payments nor were there at any stage any reason for a debt order not to go off I always have money in my account for all my debt orders, never has nedbank notified me letting me know that I am behind payments. Nedbank is ruining my accredibility.