Dissatisfied

My sister's was de*****ed R15000 from her bank account because an agent at mtn assisted a person unknown to her with a sim swap of her number and thus making her unable to see any bank notifications on her account via sms. As soon as she was aware of this she went to an mtn store at Cresta but was still not assisted and was told that the person who made the swim swap is still using the number and she must call the call centre which she did but to date could not recover her number until she decided to change to a new mtn number that was working from Saturday but now she cannot receive calls nor sms as it says it's not available on the network. I need mtn to give us solid answers because in order to do a sim swap there are security questions asked and if you are not the owner of the number then you are not privy to that information then you would not be able to answer those questions and we suspect that an mtn agent that did the swim swap is somehow involved with this ********** activity that went on her account. We need answers from mtn urgently