Failure to understand / resolve complaint timely

On the 15th of June, I had R600 deducted twice from my account. I don't know how or who deducted this amount. The same double deduction of R600 each happened the two days later on the 17th of June. Two R600 were then reversed on the 18th of June. Rhea Singh could not explain why 4 debits of R600 took place and why only 2 R600 were refunded. She kept saying I should not complain because the money was refunded. Also, I had a similar issue with Food *****s market R190.77 and Spar R84.93 and Mr Price R79.44. There were a total of 2 debits and only once credit. I had to write many emails and phone many times and eventually she agreed to send me a complaint form. I fail to understand how a banker could not understand my complaint and I had to waste so much time complaining and even highlighted my complaint in different colours on the emails I was sending her so she could see where the problem is. I no longer want her as my banker and I want this matter investigated and my monies refunded to me and also I want to know how this could happen in the first instance. I have no trust in Nedbank if my account can be debited like this without any explanation