Unfair penalty charge for debit order

I have a problem with the Private client service suite.i was on secure chart with Modisaotsile Mangwathe trying to understand the penalty charge of R400 on my account. I am now overdrawn with R500 and I was advised it's because the bank paid for my 2 debit orders when I did not have money. The debit order is R1500 and R34.66 but when I check, the negative balance is due to the penalty charges.so this is not fair. I am asking for this fee R400 to be reversed please. Thank you