Number being Hacked, No help from Mtn Consultant

I received a phone call from a guy called Ntando saying he was from MTN they noticed that someone was trying to hack my number asked me a few questions on when last did i recharge, how much airtime did the put in the last three people i called. After that phone call my sim card went straight to emergency phone calls. I than called the MTN customer care the consultant i got there couldn't even helped me, just told me that someone did a sim swap with my number. I don't understand why didn't MTN notify it's customers about this ****s that are taking place. As we speak now this people took all my money from the bank.