Telkom: No assistance via call centre nor website

Telkom please can you assist for once. My mum has a home landline that needs to be cancelled. We cannot cancel online (registration keeps bombing on us), so we cannot cancel on the website. We try to call, but they keep telling us to cancel online. We are going in circles with Telkom. The landline has not been working for a year now, every time I call they promise that someone will come through, but no one has come, all the while we are still paying for the monthly service. So now we just want to cancel. We are frustrated to say the least. All we want is to cancel the contract now but even that has been a nightmare. Can someone please assist, a pensioner cannot be wasting money on a service that is not working.