Vodacom: Keeps taking your money even after you cancel your month to month subscriptions

I ported my number from Vodacom after being a 'month to month' customer for a long time. Little did I know that they would assign me what they term a 'shadow' number and keep charging me for a service I now have access to (take note other cellphone customers who wish to change providers!!). I called in and was helped by a person named Vusi. Sorry about that he said - I will process your cancellation immediatley and come May 2018 you will not be charged for any service you don't have, he said. Guess what - 2 May and Vodacom took all the money I owed plus what I DON'T OWE. Yup - still paying for that SHADOW number I don't have access to etc etc. The worst is - I didn't just ask for cancellation via phoning their helpdesk. I have proof I sent a mail before that as well. Currently I would strongly advise against Vodacom - they will just keep taking your money. I am going to tell my bank to reject their Debit Orders - I can't think what else to do!!