Pathetic MTN service

My personal information has been compromised by MTN. I was using my personal cell number for work and my personal banking as my employer was not offering a cellphone at the time, meaning that I would need to do Microsoft authentication verification using my personal number when logging into the work systems to receive the verification code. All of a sudden I received a verification code which I did not ask for and 2 days later I could not receive any phone calls. On contacting MTN I was told that I did a Sim swap a week ago hence the current one is not working. I asked them how could someone unknown access my cell number without my consent and the response was that "the old Sim cards have that issue of easily being swapped". My whole personal information for over 20 years has been compromised, as I used the number for social platforms, all my banking accounts and work. What is even worse is that this same person accessed my bank account and bought airtime on that same number they hijacked from me. One question is how could MTN allow something like this to happen without my consent? Is a person's information not RICA'd to avoid such things as and when you contact any of their stores. If MTN is not protecting my personal information, am I now supposed to sort myself out? This is pathetic and unprofessional on so many levels and now I have to go to 3 banks to try and recover what is left of my personal information.