Charged extra R100 on my bill

<p>I have an account with Vodacom which I pay R199 p/m. Last month I had to change my banking details with them and I was informed that the debit order won't go off the same month I had to pay manually. I did the transfer and to my suprise they also debited. I reversed R199 as my account was uptodate. This month my account was debited with R299. Will you please rectify this and refund my money. My vodacom account was not in arrears. I hope this will be corrected as a matter of urgency</p>