TELKOM CANNOT BE CANCELLED

I have been trying to cancel my mothers account for the past few months. We went to settle her account, requested a cancellation and were told to go online. We did, entered her ID, and we see a notification that there are not accounts for the ID entered. Which we assumed meant that it had been closed as requested. Now we are getting a final letter of demand for an account that was meant to be closed. The woman is 83, is deaf, and has Alzheimer's. DO BETTER! WHY CAN'T WE CANCEL IN STORE?