Extremely bad service

My phone was ****** in May 2024 and I did notify MTN to block the card because it didn’t have a PIN but up until today they didn’t and whoever stole my phone is still using it. What worries me the most is that the card was on Superflex which is still deducting even today. I have tried cancelling the subscription but no one seems to care, they keep on telling me that I should use the MTN app to cancel but how when I do not have the sim card with me because when you log on to the app it sends out the OTP to that number, and the call centre is also useless because they just drop the call while you are still explaining your story. I really don’t know what to do anymore