Help!!!

My mum in law is currently going through a very difficult situation where her tax number is apparently not valid and needs to be reinstated but surprisingly nobody at SARS can assist her. She was told to go through the process online but to no avail. Now she has been asked to make an appointment online but still it requests her TAX number which is INVALID!!!! This is very frustrating and confusing. She has been to her nearest SARS offices and even consulted the manager but nobody is helping in this regard. This is very unprofessional service considering She is a pensioner and is being sent back and forth with no results.