Charged R 623.00 by FNB, the worst bank ever.

So FNB decides they will do as they please in my bank account, the charged me R 450.00 for #Item Paid No Funds 3 Items On 20/07 which supposedly is because they paid for my items when i had a negative balance on my account, but on the same day this charge was initiated my running balance was R 135.00. As if that was not enough they come and charge me R 60.00 for another #Item Paid No Funds 1 Items On 20/07 and another charge for R 110 which i don't know what is it for. Now my account if on a negative balance of R 623.00. When you complain about this kind of charged they don't respond back.