Delayed service resulting in extra bank fees!!!!!!

So i think Ive had enough of this now. when i purchase anything with my card, at some merchants it does not go off immediately. i then use my money and at the end of the day my account goes in a negative then i end up having to pay overdraft fees, the money that gets deducted that causes the acount to go into a negative, i dont mind to repay as i did use the money. but what makes me fed up now is that i left a R300 in my account for my debits to go off (R165, R36 and R36) then 3 merchant transaction went off after this resulting that i do not have enough money in the account for the debits so i get charged R115 penalty fee for each debit that did not go off. i do not keep track on how i spend i checked my balance and drew money leaving the R300 behind, however my bank statement says something completely different. i dont mind paying the the money, like i said its money that i spent, but i cannot pay R500 to get my account to a zero balance then another R300 so the debits can go off. and what sucks is standard bank will try to do the debit weekly even though there is no incoming funds resulting in more penalty fees, and i think its unfair that i have to foot the bill.