Debiting after my contract has expired

I sent an email to MTN customer care on the 25th of May 2015, requesting that they stop billing my account as my contract period for two top up accounts has ended. I opened two top up contract accounts in February 2013 and both these phones are now paid up. I no longer need or want the contract but MTN has not given me any feedback to my request from 25 May 2015. I want a refund for all the money that has been ********ly debited from my account and immediate cancellation of all contracts in my name.<br> <br> I DO NOT WANT TO BE CONTACTED BY THE CUSTOMER RETENTION DEPARTMENT AT ALL. <br> <br> The automated response I got from their customer service email address, just gave me a reference number ***7 and nothing has been done since. The reason why I contacted them via email is that I am out of the country and require email correspondence. I am really unhappy with the service that I have received.