Nedbank Turns a Blind Eye

An amount of R8.60 is being deducted from my account, more than once daily. This keep on happening that my account goes from a positive to a negative balance non stop. Nedbank don't respond on queries about this deduction. Various emails were sent and phone calls were made without any success. The same happen to my son with his account. The feedback he got is that a debit order did not go off and that is the penalty for the debit order. Firstly all our debit orders are honored every month and are deducted by the 1st of every month, secondly this transactions take place throughout the whole month, and multiple times a day, there is no proof of an unpaid debit order and if and that is a big if, if it was foe an unpaid debit order why multiple deductions per day, why not only once, why not contacting the customer and inform the customer of the problem, is there no ***** division monitoring this type of transactions, and if there is does it not look suspicious?