Cancellation Request

I cancelled my contract with 8ta (Telkom Mobile) in March 2015, till to date I am still being billed for the contracts that i have long cancelled. I dont know how many times I have called Telkom Mobile to fix this issue and everytime its promises that are not met. Everytime I call I am told of a system issue that is delaying the cancellation but I mean really 3 Months...My two case numbers are ***6 and ***4. I even went to bank to cancel their debit order with the hope that someone will listen but yet I still receive invoices soon this will impact my credit scoring.