Trying to Cancel a debit order with Cell C Mission Impossible

I am trying to get my debit order cancelled with cell c, what a mission from getting customer services Consutants shouting you down etc, conversations got rather heated and still nothing is done, the debit order will be coming off a closed bank account but that does not seem to bother the customer services consultant and then I was charged a penalty on top of everything after I notified cell c that I will no longer be paying via debit order but via the app