Extremely dissatisfied and still not helped

Cell.c is pathetic i have a prepaid sim card with them for well over a year, which was ricaed by me using my ID number. I get a sms saying it is now ported to an mtn number without my knowledge or consent. How terrifying to know that all my personal information as well as finacial info could stand a chance of being violated. I call Cell.C and nobody could assist. More over how could cell C allow this to happen shouldnt there be more secured ways of doing this after all in this day and age having your cellphobe number taken over is just as good as having the combination code to your whole life.