Cell C *****ulant activities

I have been struggling now for 6 months trying to stop CellC from debiting my bank account for a phone and contract I do not have with Cell C ( and i can say it is not peanuts it is thousands they are *****ing)- I have canceeled my contract wit Cell C and all of a sudden they are debiting my account again monthly with thousands, i enquired and they said i received a new Apple device and cell nr and i am still struggling to put and end to it. i have called many times and i did the whole *****ulant query as well - but no-one is getting back to me - it is really disgusting!! and you ask them to call back because you are in a meeting and then they never do. They gave someone a Cellphone and a cell nr on my bank account - that is very sleazy!