Dishonoured by my bank

I'm extremely unhappy to find out the hard way that when a debit defaults on my business account I am charged a whopping fee and sent a ridiculous message about it. Firstly I pay a tonne of bank fees every month. Then I pay FOR EACH TRANSACTION that I make on the accounts that I already pay for. Now you want to charge me almost the same amount as what the debit was for a simple mistake with ZERO warning. Where does it end? I STILL need to spend half the day on the phone to rectify the situation with the debitor. FNB you provide ZERO service, but you want to charge me fees upon fees upon fees. And to use the term 'dishonoured' is actually insulting. I've been a client for years, but this is too much.