Vodacom Overcharged

This is the third month in a row that Vodacom has over charged me on a Top Up package!! How is this possible?? At first is was R300.00 over charged for handset installment, then another R100.00 for handset installment and this time R1140.00 for some cancellations request that I don’t not even request for! I have been calling the call center , accounts department and the cancellation department and it’s seem non of them can help me with this issue. I’m a pensioner and they are not willing to assist. I cannot wait for this contract to come to an end so I can cancel and move away from Vodacom. Very unhappy customer!