Delaying tactics in Termination of Expired Contrac

I have a MTN cell phone contract that expired in January, which I cancelled in Janually Via Email. I got a response saying it would be terminated on 12 Feb and Migrated to Prepaid. Nothing happened in February and they continued Billing me, including for my device which isn't theirs anymore. I instead got an email on the 25th February saying that I am going to forteit some small amount like R 40 of air time if I still wanted to terminate and asking if I still wanted to cancel. I didnt see this mail until after the 21 of March and responded to it asking them to terminat. Nothing happened. I then called them on 7th April asking them to cancel and they gave a refence and told me the turn aroaund time was 2 to 48 hours. I am still waiting to this day.