FNB Took R830 will Ref #ITEMS UNPAID! R830?????

FNB has taken R830 from my account with a very 'clear' reference of #ITEM PAID NO FUNDS. Right before payday a transaction was declined due to insufficient funds - Is FNB charging their fees in Dollars???? This has happened in previous months but to the amount of +/- R200.00. I will not accept this! It's daylight *******! I called FNB this morning and an assistance advised that FNB have taken these funds for purchases I've made with my card while there are no funds in my account. Yes the 2 days where this supposedly occurred, I had not used my card as I knew I had no funds! Maybe it's time to look into other more reasonable banks like Capitec.