Paying for data that cannot be used.

I have a data sim card with MTN but when I'm trying to connect to it, there is a no funds message although the sim card has 19.33GB of data. I called MTN almost every day since last week (2019-12-02) but the issue has not been resolved. Please can someone from MTN resolve the issue, when I called again yesterday the agent told me that the issue has been escalated.