Vodacom contract cancelation

I phoned Vodacom Cancelations in August to cancel my data number, and was told to phone back on a certain date in October, when I phoned they said I must phone in November to cancel, i phoned again and the consultant said all is in order.....only to find out they have been debiting my account in Nov and Dec...i phoned again on Christmas Eve only to be told they need to investigate and there is a possible refund, in addition they cannot cancel due to the investigation, Today I receive an sms to contact the retentions and not one of the 4 times i phoned do consultants know why i received and sms. All they want to know is why I want to cancel. Vodacom thinks they have monopoly but the bigger one is the harder they fall. Get your act together as with this type of service will force customers to join your competition.