MTN billing is a nightmare!

I had a data contract with MTN in 2014 and renewed it in 2016. I cancelled it in 2018. I went to MTN KeyWest and they told me to phone the third party to cancel it. 24 Aug 2018 I cancelled it, however MTN continues to deduct the amount from my account. I phoned the third party on 20 Jan 2020 and spoke to Carl who promised to cancel it. Yet nothing changed. I phoned MTN Head Office on 2 October 2020 and spoke to Anishia *** who promised to stop the contract and make sure I receive a refund. This morning, 3 Nov. the amount was deducted again. I am highly dissapointed in the service I have received from MTN and I would really appreciate it if someone could resolve this issue.