MTN security breach

My sim card was hack via the MTN application. The hackers then did an online sim swap. For personal reasons I am not able to go to a store to do a sim swap. I have reached out multiple times to MTN for assistance. This has been ongoing for a week. They just do not want to think of way to assist me. In the meantime the hackers is using my WhatsApp to contact all my contacts pretending they are me and asking for money.

How can any MTN customer feel safe if your sim card gets hack via the MTN application?