Feeling like I am being ****** by my bank

I have so many issues with FNB right now. I have been a client for 10 years. Currently a private client. My company changed my salary date from the 15th of each month to the 28th. I changed this information on my banking app. On the 15th FNB attempted to deduct a device payment of R289. I only had two payments left before the account can be closed. The amount didnt go through. On the 16th I informed representatives to deduct the amount on the 28th which they did. Pn the 3rd of May they attempted to take the amount again stating it is for the May payment which should only be the 28th. I have received many calls in this regard, each time explaining the situation and stating that the April payment was successful. I even called the private banker for assistance. Fast forward 3 weeks later I have received letters of demand - even though I logged a dispute and have spoken to many agents. FNB now stating my May payment is in arrears - I usually make payments at the end of the month. They have alos added R289 to the total outstanding balance (extending the period of contract with one month). This prompted me to look at my bank statements, which I do not do often. I see many interest deductions on my account and penalty fees of R1511 for items supposedly unpaid starting from the 19th. It is amounts R8.50 a few times a day declined foreign tra/for transaction. From my statements it seems that amounts reserved for purchases are taken later (the merchants fault apparently). My issue with this is - if I know have x amount of funds available in my account and swipe for payment, and then get a notification that the funds are reserved and deducted from my available balance - why am I being charged weeks later and then penalised for unpaid purchases when it was clearly paid. My next step to resolve this matter will be NCR/ombudsman. I have not gotten a new credit report yet but if the so called arrears on my device reflects on my report I will make making a formal complaint. I would like FNB to do their homework and explain exactly what is happening with the account - now it seems my account is just out of control with deductions and mostly from FNB themselves.