Contract cancelled but still billed.

I upgraded on telesales and when I received the device I wasn't happy then I cancelled. they told me the cancellation was successful, then I realised I was being billed on that cancelled contract. I then called Vodacom the told me it is arrears they wont bill me the next month. I checked again and hey I am still being billed. called the again today and they telling me stories that someone didn't authorise the cancellation, they will get back to me in 3 working days. a bunch of ****. I want to be reimbursed my money and all the inconvenience caused.