Nedbank charged me 4 x R90 HonFees on one day

On 23 November I logged into my internet banking and saw that on 20 November Nedbank charged me 4 R90 HonFees for transaction done on 18 November. When I inquired about this, they told me I was charged those fees because there were not sufficient funds in my account. I did not know that there were insufficient funds, otherwise I would not have done the transactions. Often when I do a transaction, Nedbank does not immediately reserve the funds and the transaction will only go through a few days later. I cannot keep up with which transactions has gone through and which not as I do not get sms notifications after each transaction and when I do get, it does not state what the my current balance is. The concept of the HonFee has never been communicated or explained to me in all the time that I have had this account. If there are insufficient funds, Nedbank should decline the transaction and not let FOUR transactions go through on ONE day just so that they can afterwards charge me hundreds of rands for it! I do not feel it is fair that I should pay the HonFees as I was under the impression that there were either sufficient funds or the transactions would be declined it there weren't.