Account cancelled but the debit orders keep on coming off!

Good Day My Netstar was cancelled on 15 October 2015. They failed to inform me that you have to cancel the Netstar Go separate to the main Netstar account so a while later I noticed my account still being debited by Netstar. I then called Netstar to query the debit order and was only then informed of the separate cancellation that needed to be done. I called Netstar Go around January 2016 to cancel. I noticed in April my account was still being debited. I chad to call again to find out why. Apparently they did not log the cancellation in January. I asked for a refund of the money that was deducted and received no reply. It is now May 2016 and again, my account was debited. So you guys have been taking money from me since October 2015 even though my Netstar was cancelled. This is totally unacceptable and your call centre is totally ***********!