Bad bad service

I can't believe I have received such bad service from MTN for the past week now. My phone broke and my Sim card is damaged. I went in to get a Sim swap. Then they told me I cannot have a Sim swap because their systems are not working. I explained to them that I need my Sim card for job. I am a teacher and have learners on camp who needs to return home and I cannot communicate with them or their parents. They mentioned that their is nothing they can do. Now I am paying for services I can't use. When I asked to cancel the contract so I can do a pay as you go Sim swap they explained I need to come back tomorrow and the process must first accept the cancelation of the contract before I can have a Sim swap done as they are changing systems.

How can they change systems without notifying their customers and putting replacement measures in place as I am paying for services I cannot use. Plus my work and personal life is suffering due to their negligence.