Unsuccessfully trying to cancel unused contract

I had an airtime contract with Edgars on my old number, but in August 2014 when I changed my number I requested them yo stop the contact as I no longer had access to the number they were providing the airtime too. It is now 8 months later and after several calls to their call center and numerous visits to their Branch at Loch Logan waterfront mall in Bloemfontein they have still not cancelled the contract and keeps taking money from my account every month I am deeply unsatisfied with this and I am planning on promptly closing my account because of this