Been Charged Additional Fee for Vodacom Problem

I have a complaint about been overcharged for a problem that Vodacom had. For the last almost two years there has never been a problem with my debit orders going thru last month February 2016 Vodacom had problems with double debit orders going thru on customer accounts and debit orders that has been reversed, for their problems they had, the customer know has to pay extra, I was debited with a double payment and a added R100.00 on top of that. I then request that I want an e-mail address where I can sent a cancellation letter to as the contract is expiring soon and get told that I can only get a e-mail address when the contract ends. This is not acceptable and I will not pay an additional R100.00 as it was taken out of my account without my consent and I was also never informed about the additional R100.00 taken from my account.