Irate customer

For months I've been charged penalty fees for fnb honoring payments due to insufficient funds in my account, I asked them so nicely to remove that option from my account and they agreed they would, but to my surprise fnb still charges me that amount yet the payment wasn't honored, I wouldn't go to the shops to buy something knowing I didn't have money to pay for my items yet for some reason fnb still manages to charge me R150 on top of the R300+ they charge me for. Monthly fees. The agent I was chatting with(Pilani) took over 10 Mins to respond, but when I type a 5 mins long response she cancelled the chat. What nonsense and service is this.