Telkom pathetic service

I called the Telkom customer care sometime in March that I will not be upgrading my contract because of network coverage therefore I cancelling my contract. Only to my dismay it May Telkom is still debiting my account and when I call apparently there’s is no cancellation called and my call was never recorded on their system. It shouldn’t be my problem for the incompetence. Telkom my sort out it’s I let the April debit slide but not the May debit will not slide.