Inferior customer service

I have taken a Device contract with MTN in October 2023. Since the device was delivered, I was not able to use the my SIM as data and voice bundles allocate were not working. I have been calling in and sending emails, they all telling me to refresh my device and everything's should be working fine. This is the 3rd month having the issue and it has gotten worse, the sim card stopped working and they telling telling me to refresh my device even today 3 months later. I deeply regret taking a contract with MTN. All the agents are ***********, I have spoken to about 15 agents so far plus 4 supervisors and they all hang up once you start asking them questions.