Failure to honor request for Debit Order Cancellation (since May 2017)

In May 2017 I requested my dsTV subscription to be cancelled. My first call was made on the 15th of May where I was told by the operator that the 'system is down' and that he made a note for cancellation. I was on the phone at least 30 minutes trying to explain why I wanted my debit order cancelled and repeatedly asked for confirmation that a note was made for cancellation. I was assured it would be cancelled. Fast forward until November 2017 I discovered that they deducted the premier subscription monthly despite the cancellation request in May 2017. I take ownership for only realising this in November, however I immediately raised this on 25/11/2017 (reference number ********** 6-I12 ) and was again assured that my subscription was cancelled. I had to remind Multichoice several times on their website "contact us" to refund me for June - November 2017 which they did in December 2017. It was with utter dismay that Multichoice again deducted a double month (2 x premier subscriptions) in December 2017. I honestly do not know what to do as this company is blatantly failing to honor a lawful and reasonable request.