FNB continues to ***** money through Excess Items charges

FNB has become very efficient at *****ing money under the 'Excess Items' plot. I have a business account with them where after debit orders have been concluded on the 1st of each month, I transfer all cash into an interest bearing account. FNB defers debiting my account to the 2nd of the month so that they can charge R155 per transaction for the debits. They only debit once the cash in the account has been moved so a negative balance reflects, then they charge for Excess Items. This is theft and how does one challenge this?