Charged without my consent

I have 2 personal loans with Nedbank. they debit my account on the 25th of each month. One loan is for just over R3100 and the other is R194. At the end of June on the 25th they debited my account with R194. The other loan R3100+ did not come off. I then waited until the end of the week as Nedbank will take the money as soon as I get paid. Next week come still nothing. I then got a call from the collections department asking about the loan R3100+ not being paid. I then asked them why they did not debit my account. They could not give me an answer. For them they said there was no funds in my account which was incorrect as I have over R11000 in the account. On the 10th July 2018 I was in immediate need of cash due to unforeseen things. I then went to take a loan out through African Bank. In which they paid the money into my Nedbank account. being the 11th July 2018 today I made arrangements for the mechanic to fetch my vehicle to sort it out. little did I know Nedbank took R3100+ out of my account which was there error in the first place. Now I cannot reverse the amount as they did advise I cannot reserve this. So basically I took out another loan to pay off this loan does that even make sense. I spoke to Sara at Old mutual branch in which she was very understanding. But advised me that I cannot reserve this as well. Please advise me what the next step is as I told Sara that im paying my loans up and moving to another bank as Nedbank is treating me ill.