Account issues

I have erroneously been debited for an amountexceeding my monthly contract amount. After querying this I was first informed that I would be refunded the money within in two weeks but told to phone back in a day or two to confirm. On phoning back I was informed that the amount would be refunded in 48 hours. Today I was informed that the money will be credited to my next debit order only. I find this shocking as I have other commitments and now I have to wait until the end of the month to be refunded when this was an error of Vodacom. And I'm pretty sure they won't reimburse me the interest on this money either. I am also extremely annoyed that since upgrading in April I do not receive any statements so I am not even warned prior to the debit order going off. I still have no statements and therefore still cannot ascertain what is the correct amount that I should be refunded as the amount R840,00 seems less than what it should be. I cannot create an online profile as both times I tried I was told the system is experiencing technical difficulties so I can't register there either to see my account info.