Struggling to do Sim swap

My mothers number was ported by ****mers that were trying to do mobile banking transactions about 2 weeks back. Fortunately they were unable to log onto her mobile banking, however, she ended up losing her number. We have been trying to do a Sim swap in order to retrieve her old number as this number has been with her for years now and we are not getting anywhere... She even went to the MTN outlet in Ladysmith and they still didn't assist her. Please could someone contact me so we can get this sorted out ASAP as this has shown poor service from your side...