mtn blocked my number to never call customer care

I called mtn asking why is it that when I have to make a phone call it says I have insufficient airtime whereas I have airtime and the lady said I should switch off my off my phone and on again. so I have asked what if I have an emergency I am about to give birth and need to call my doctor should I still switch it off and she gladly said yes. I told her its the fourth time I am calling about this issue she said there Is nothing they can do I should just switch off my off. Then I asked to speak to her supervisor she said she is still busy on another line then told her I will hold, they made me hold for 5 minutes then sonto \the lady who was assisting me"came back and said the supervisor is trying to call me I should hang up"