UNAUTHORIZED DEDUCTIONS BY MTN

I had a contract with Mtn which expired in April 2022. I called them to cancel and I was told by the consultant that the last day of my contract would be 25 May 2022 and I must make sure that I exhaust any data available before that day. From June until this day they have been deducting for a contract that I do not have, they even threatened me that should I not pay them, I will be reported to the credit bureau. I have sent numerous email, called them many times without receiving any response from this ******.

What can I do to get them off my back? Please help.