MTN's ***** contract cancellation is a ****

I ordered online the MTN 5G fixed home router (20/10mb) month to month contract in October 2024. My debit order was going off on the 15th of each month. In December I went to MTN Sandton to enquire about cancellation. I was advised I need to bring the router with all the accessories it came with, and since my debit order goes off on the 15th, the best time to cancel will be the 15th or 14th. So on the 14 January 2025 I went to MTN Sandton city with the router and all its accessories to cancel. I was told the cancellation was done and issued a cancellation reference number. On the 15th January the debit order went through, that was fine as it was my last one. However on the 12th February I saw an email from MTN with a statement of R R 494.99 that is due on the 15th February 2025. I then went to MTN to check and I was told the cancellation I did on the 14 January was not successful and that there was an error/system glitch when the consultant was loading the cancellation but it was not my fault. The consultant adviced that I can reverse the debit order if it goes off on the 15 Feb whic it did and I reversed. Now I am getting SMS that I owe R494.99 I should pay before they hand my account to the credit bureau.