EXTREMELY TERRIBLE SERVICE, DAY LIGHT ******* AND BREACH OF CONTRACT

FNB has decided to charge me over a thousand rand as of July as Int debt fee which was never there before, and this was not discussed with me, Since when do I get charged and INT DEBT FEE ON OVERDRAFT ACCOUNT, I notice this started in July 2024 until date. How did this fee got introduced without my knowledge and consultation, Which contract was signed in agreement to this?, i need answers or else i will ask other banks to buy me out then they will be left with their Int debt fee which was posed to me. How can they decide to take over a thousand rand in my account without consulting me?