Cancelled contract but stilled billed

I did an online upgrade with Vodacom in January. I cancelled the upgrade they came and took the device.. But they didn't cancel the contract even after I called to cancel it. My invoice say 3G laptop, when I took the contract it was not a laptop. I'm paying for a device I don't have. When you call you get sent from one department to another but they don't ever help.. I would like to be refunded my money. I want to cancel all my dealings with Vodacom can I have a settlement statement for my existing contract emailed to me asap, I'm not happy with your service.