MTN Keeping Me Hostage

I have been trying to cancel my contract with MTN for the last 3 months cancellation was done on 15 November 2022 and now on 15 February 2023 I was still not successful and they keep on billing me and I am not getting any feedback whatsoever. I tried again phoning today have spoken to 3 different people had two dropped calls and still no answer, just getting transferred from pillar to post.