Unpaid items charges

I have a premium cheque account with FNB without an overdraft. I noticed this morning that FNB charges me a fee every month after they have debited my banking/service fees. This charge 'Items paid no funds' is supposedly because they honor a transaction I made when I had no funds. The issue here is that i have never swiped my card with no funds available and i make sure my pending purchases will be honoured. There is something wrong with the banks response time as sometimes i wake up with a negative because they take 5 days to show a purchase. I do not want them to honour a purchase if there are no funds. Why must i pay R110 for an item that maybe cost me R17 because they do not update their system efficintly. This hasnt been a problem until this year. I want all the debited amount refunded to me.

I made a purchase when I had funds, obviously the merchant didn't bank it immediately and obviously the bank reserved the funds I had in my account for that transaction. Then my bank fees were debited and put my account in a negative balance, but FNB then used the funds reserved for the purchase I made previously to cover the bank fees and by the time the merchant banked the transaction there was supposed no funds. I feel that it is absurd for FNB to be charging this fee, knowing I had money when I purchased to cover my purchase, also knowing that a merchant never banks something the same day. Also knowing that I have no overdraft so if I essentially swipe my card and don't have enough money my transaction would decline right there at point of sale.

Obviously they don't but why that charge when they can see there was money at the time I bought and it is the process between banking the transaction and what happened in between when the bank debited my banking charges/fees that pushed my account in a negative balance. Why must I the client then pay the bank an extra fee on top of all their already expensive charges when the merchant banks after the bank debits my banking charges/fees monthly? The bank knows very well they did nothing for me. They did not honor any payment for me. This is day light *******. I get nothing for free so why does FNB expect me to just hand over my hard worked money to them? When I investigated my last 4 statements this morning I have picked up that FNB does this almost every month when I happen to make a purchase when I have funds before my monthly service fees are debited, then they put through their fees, it takes up the funds that were reserved for the purchase I made, the bank fees pushes my account into a negative balance, and the merchant banks the transaction the woops there comes the charge 'Items paid no funds'.

If this is not fixed, i am closing the account today and going to another bank.