Telkom is a ****

Hi I've a contract with Telkom whereby my debit order returned unpaid for the 1st time. Which I pay R105 Telkom charged me the penalty fee of more than the amount I'm paying how is that possible, again they attempt to debit on the 17 August which is not my debit order date. My bank is charging me the unpaid debit order fee due to Telkom poor services. Are guys the bank or service provider whereby you charge people more than double the amount that I'm contracted? And who gave you authority to debit my account before the debit order date? Is that in my contact?