Very, very, very bad service from MTN

I know all the cell providers are just awful, but it seems that MTN is now becomint the worst of the worst. A few months ago there was a major accident in front of me which I attended to, but at the same time my phone rang to say that somebody is requesting a simswop on my number. Dealing with the issues in front of me, I didn't think to much about the call but told the person that he must immediately stop the simswop. He kept me on the line and asked me for the OTP that came to my phone. While talking to him I started feeling uncomfortable because he didn't ask me my security questions (as Vodacom did a few days before). So I asked him my security questions, and he knew all the answers. I also tried to google any MTN ***** issues, and there was none on the internet. Finishing up with the accident, I could not shake the uncomfortable feeling about the call and checked my phone again. I then saw the sms's of data being ******. I tried phoning the ***** line that I found on the internet - it did not exist. I tried phoning 135, still no help. I then went to the police station. They phoned the nearest shop (we don't have one in our small town), and stopped the ***** from continuing. They also told me to make a statement at the police and bring it to them. They told me it happened to hundreds of people that day and that I must not worry about it, that MTN will resolve the issue. It was not resolved and I now have an account of over R16000. I would love to know why is MTN not protecting it's clients? (I have been one since 1992). This person was inside their network. He saw the answers to my security questions. All of this is MTN's fault. I tried protecting myself, but being distracted I probably did not do enough. Why are we just accepting this bad service from our service providers? I cannot be without a cellphone, so where do I go from here?