Still paying for cancelled contract

I have cancelled two contracts I had with MTN 21 January 2016. The ref # for the cancellation for the t wo lines: *** and *** is #***5. I received an e-mail from the retention department 22 January that confirms my request for cancellation. It has however come to my attention that I am still billed - and it is now APRIL 2016. I have phoned the customer care line 30 March in this regard. The agent said that on the system MY LINES HAVE NOT YET BEEN CANCELLED. She would have sent it to her supervisor for immediate cancellation, and would have sent me that e-mail as well. (Ref #: ***) I never received an e-mail. I would have gotten a response within 48 hours. I have received no feedback. I have e-mail the retention department as well as the customer services from which I received 22 January both on 29 March and 30 March. Yet, I have received no feedback. I have tried to phone the customer care department again 1 April, but after 60 minutes no one answered the phone. I want the lines cancelled with immidiate effect, and the costs of March paid back to me for both the lines as it was MTN's mistake that I am still paying and not mine!