I can't seem to get my contract cancelled

On 6th February 2015 , I wrote to Altech Netstar regarding my account ***, which i wanted to cancel as the vehicle containing this device was written off in an accident.<br> I was sent a confirmation that it had been cancelled by Nthabiseng Motsene. Since then, i have had to call every month to inform them that they are still debiting my account.<br> Each time i am told they will look into it, and every month the account gets debited again.