Money deducted for no apparent funds

I’ve been banking with FNB for the past 7 years and I was very upset when I noticed that I am being charged regularly for ‘items paid no funds’ when making purchases yet my account has and shows funds. This is ridiculous because I’ve been charged over R600 just for the month of August for apparent insufficient funds yet my bank account shows that I have available funds. I contacted the bank and was told that I need to manage my account and always look at what balance is available before spending as if I’m an idiot to go and spend money that I do not have. I was then advised to send a complaint to the complaints department yet no details were forwarded to me. This is pathetic and the saddest part is that not even my advisor has been in contact trying to assist me further with this matter! If this is how FNB goes around ****ming and *****ing then I need to find a bank that will be transparent. Can someone please assist me to solve this matter.