Iniquitous penalty fees

I wonder on what basis Vodacom is entitled to charge R100.88 for a declined debit order which itself is only R329. It would seem totally out of line. Where in the contract is the penalty mentioned and quantified? As usual Vodacom is fleecing customers. It is a behemoth with archaic customer care facilities.

Please justify the charge. I have subsequently changed payment option to direct cash payment, but I wonder how many people don't have the liberty to do this and get charged monthly iniquitously large sums of money. Does the quantum comply with the Consumer Protection Act?