Contract cancellation

I have two contracts with MTN and have been trying to cancel one for over a year now. I call into their retentions department every week and each time I am promised a cancellation and a refund. The last two people I spoke to are Themba and Kwanele who promised me that I will receive a call within 24 hours. I’d like to put this to rest now, get what is due to me and a cancellation that I am supposed to. I am truly sick and tired of calling in.