FNB bank charges - unhappy customer

I think today is the official day I use FNB! I am disappointed in their service, I’ve been complaining about their bank charge and it’s still under investigation! For how long! Because I want to use my savings pocket, and if I transfer the money out, it’s technically net off against the negative balance of supposed bank charges. So my complex changed electricity service providers and we were informed to buy electricity by the 31/10/2022, as from the 01/11/2022, the service will no longer work. In my attempt to buy electricity on the 31st, transactions were not processed, and therefore, money is paid out of my account, and then immediately repaid back in as it is credited back because the system declined, I attempted 5 times. Fine! Now the money immediately transferred back into my account (have proof) therefore leaving me with an available balance which according to the app and my knowledge, was sufficient to pay of the remaining debit orders. Next thing I see a bank charge of 870 now for things paid when the was insufficient funds, mind you I repeatedly checked my available balance, so I knew the was enough left! So I demand that Fnb reverses those charges! What beats me is that, I have had a transaction bounce back due to insufficient funds, and it alerted me, why wasn’t I alerted if these ones! Debit orders bounce back, why didn’t these ones! They cannot charge me for their app which is not synced to their system or whatever the case is! Please fix this