No refund for cancelling my contract on time

I have made serveral attempts to give more than 30 days notice to MTN to end my service contract. My contract period 24 months has ended ( data contract - simcard only - My gig 50) , i did not wish to uprade, so more than 30 days ago i started to give notice. Everytime i logged a query or opened a ticket, MTN would close it and NOT resolve it, no attempt to contact me. I have made several attempts, please see attachments.

So this month, MTN bills me R1721 from R366 because they have failed to close/end my contract. I have done everything correctly in terms of my agreement. I cannot and will not pay this R1721.

All attempts email and telephonic have been unsuccessful.

So i have opened another ticket to get this resolved.