#ITEM PAID NO FUNDS 2 ITEMS ON 20/10/

Why am I being charged #ITEM PAID NO FUNDS 2 ITEMS ON 20/10/ fees of R 300 and another one of R 110.00 for transactions that happened on my pay day when there was enough money in my bank account. How is it my problem that the money was not deducted at the time but only after a few days. This is a lot of money just to be taken by the bank for something that you have control over.