cancelled but keep billing me

I cancelled my contract 21 days ago because my contract ended but telkom billed me R600 extra for data i didnt order. Now the new month has started they have billed me again for the data i didnt order and are asking me to wait another 21days to get my refund. Unacceptable. How can you take money from my account without me ordering anything and even after i have cancelled my account?? I want my money back into my bank account not my telkom account because I wont be dealing with telkom again. And the call agent sibusiso has confirmed with me that i will get a call from his manager at 11.15am and i have received no contact from either of them.I refuse to wait any longer and want my money back today!!