Impossible to cancel contract

I took out a Telkom mobile internet contract last year and since moved over to a fixed ADSL contact with Telkom. During the day I have Internet access at word and the ADSL at home, so I have no need for the mobile contract. It took more than a month and a Hellopeter complaint to actually get some one for Telkom to confirm what the cancelation cost will be, this person said I can just send a mail if I want to go ahead with cancellation witch I did. When I phoned later in December this mail was nowhere to be found. Went to the Local Telkom Mobile shop and did cancelation there in December. Phone in January, was told they did receive my request fromm the branch but no feedback from back office. Phone twice in February, still no feedback from back office. I did inform them that as per the contract my 30 day notice has been fulfilled and I will do a stop payment for their debit order end February (which of course will cost me money) but what else is there to do, as it is clear that this matter is not getting resolved. Latest query number received ***1