Billing after contract cancellation

I have officially cancelled 2 of my cellphone contracts well after the 24 month period.<br> This was done around the 19th of April 2015.<br> Ref No *** 79 and *** 71.<br> Despite this and numerous attempts to understand why I am still being billed till today, I cannot receive any answers. <br> If I cancel a contract, agree to forfeit my remaining airtime and receive a reference number!!, how is it possible that I am still being billed for this service?<br> I have contacted MTN via there customer care mail=no response (24/06/15)<br> Via 808=still not response. (29/09/15 + 06/10/15)<br> <br> I am sick and tired of this. I feel that I have done more than what is necessary to cancel the contracts and should be refunded in full for all the money that I have been charged since.<br> It should be obvious that at this rate MTN will be losing a long time customer that held up to 4 contracts with them.