Vodacom *****ing our money

My debit order with Vodacom is set to go off on the 25th so I paid into my fnb account and received confirmation on the 25th. Next morning I received an sms from FNB saying it was paid and the next one saying it was unpaid. No idea why this was failed but regardless I wanted to sort out my acc as I do not want a bad record and I have always been a good payer. So I phoned Vodacom this am after double checking that the debit in fact did not go off only to get a new amount of R100 more. Checked on their website and they just laid another invoice against my account for R100. Phoned them after doing the payment of the orig amount in order to find out why there is such a high charge against my name. Apparently this is penalty fees for late payment but the contracts stipulate that payment must be done no later than the 3rd which is still 3 days away. After saying this I get told its according to my debit order date. Asking why R100 I get told that's their fees but no such fees are seen in their contracts. They do mention that late pay (after 3rd) could result in interest at overdraft rates. R100 interest is crazy hows that overdraft rates!!? *****ing just like with their price hike!