cant cancel contract

I have been trying to cancel my data contract with MTN since 29 January 2015 with no luck i have a few reference number but that doesn't seam to help. Today i was told that there was an era with the cancelation but nobody let me know. <br> I have been told that my contract will be cancelled and that a refund would be due but still im awaiting. With every month that passes i get billed a huge cost (as my contract has expired)