Suspected ***** from my standard bank account

I am not happy with standard bank. On Friday 2023/12/15 my available balance in my bank account was R411-67. I paid R300 for petrol which brought my balance to R111-67. I transferred a R1000 from my savings account ,but then noticed that my balance was R800 and something rand. This definitely did not add up for me, but I thought it was a mistake from the bank and would be rectified without me having to do anything. I bought stationery for my daughter at two different shops on Monday for R313-18 & R377-70, thereafter which I I thought my missing money would be back,but my balance was R100 and something rand. I contacted the ***** section of standard bank and explained my story. The person that assisted me informed me the reason for the imbalance was because there were items that were not cleared in my account that learned when I deposited the money. NOW MY QUESTION TO HER WAS: IF I DID NOT HAVE MONEY IN MY ACCOUNT, HOW THE HELL COULD I STILL PURCHASE ITEMS OR PAY FOR THINGS WHEN I DO NOT HAVE ENOUGH MONEY IN MY ACCOUNT. I TOLD HER THAT WHEN I USE MY CARD AND DO NOT HAVE ENOUGH MONEY IN MY ACCOUNT, THEN THE TRANSACTION SHOULD BE DECLINED. THE EMPLOYEE FROM STANDARD BANK TRIED TO EXPLAIN TO ME, WHICH I WAS NO MORE INTERESTED BECAUSE I COULD SEE THAT I AM NOT GETTING ANYWHERE HERE. THEREFORE I WOULD LIKE TO APPEAL TO EVERYONE TO PMEASE MONITOTHEIR ACCOUNTS VERY CLOSELY AND MAKE SURE YOU KNOW AT ALL TIMES WHAT YOUR BALANCE IN ACCOUNT IS. OTHERWISE YOU WOULD HAVE MONEY MISSING FROM YOUR ACCOUNT ESPECIALLY NOW IN DECEMBER.