Poor service

I had taken a contract out with Cell C which included a laptop, however close to the end of the contract I had requested the contract be canceled as I no longer wanted the data deal, that was in January, up until today I am still being debited every month and when calling to the call center I am told that they will get back to me. What are your processes with cancelations, how can no one within your business do as I request? Can someone please get back to me ASAP, or I will be forced to take matters further.