UNHAPPY CLIENT

I have a premium cheque account with FNB without an overdraft. I noticed that FNB charges 'Items paid no funds' is supposed because they honor a transaction I made when I had no funds. The issue here is that i have never used my card with no funds available and i make sure my pending purchases will be honoured. There is something wrong with the banks response time as i wake up with a negative because they take 5 days to show a purchase. Why must i pay R180 due to bank charges because they do not update their system efficiently?