Billing despite not providing service

My mother's land line was cut on January 15 because Telkom informed her that it was no longer going to provide the service. They informed her that they would provide an alternative device. This was never delivered. My mother is an elderly widow who is not technologically savvy, so despite her sending queries to Telkom via mail, she has still been billed month on month since January for a service she cannot access. She spoke to a technician who was delivering her neighbour's device, and he said that he would escalate her situation. Nothing happened.

My mother now wishes to cancel her phone line, but being without a computer, she has no idea how – if it weren't for the fact that I've been through this painful, convoluted process myself, I would not have been able to help her. And still we're finding it impossible to get feedback from Telkom on the status of this closure nor the fact that they are still billing my mother despite not providing the service.