We cannot receive or make calls and our customers cannot transfer money to us leading to loss of business opportunities

Hi Charles, when you are experiencing this kind of issue, it may be a temporarily system or connection issue, you can power off and power on your phone and try it again.
If the issue persist, you can contact MTN support in case if any thing is wrong with your line.

You can contact MTN support via any of these channels:
1. MyMTN App
2. Facebook: @MTNLoaded
3. Instagram: @MTNNG
4. Live Chat: http://bit.ly/2OC5bHz
5. Email: customercareng@mtn.com
6 .WhatsApp: 09033000001