Billing Problems and Terrible Service

I got a Data contract from Vodacom and cancelled it within 14 days as stipulated by them in the terms and conditions. I never used the device nor the data on it and after having to phone them and tell them I returned the device they are still charging me for this device and the data. How does a company like Vodacom firstly sell products to a client under false pretence and then still charge them for the products. I am being charged for data I have not used, if the amount of R1239.63 is going to be deducted from Vodacom, I will not be renewing my contracts and I will stop my debit orders immediately. My contract was cancelled in June and now at the End of August I am still expected to pay for something I did not use. My issues have not been resolved and Vodacom is definitely a service provider that will not see me again.