Insufficient funds message ??

[SlowInternet]

My mother is with MTN. This last week she has been unable to make any calls and gets an "Insufficient funds" message although she does have enough airtime and data available on her phone. She has rebooted her phone with no luck.

Any ideas ?

 

[supersunbird]

That first time it happened in the week, is when she phone MTN and logged a call with their customer support, right?