Good app to use and buy airtime and data

I'm having problems with the the airtime sharing, both with your ussd code and on your app. Iv been trying to create a new pin. It just doesn't work: on your app it says it...

To convert borrowed airtime to data

Please how and what are the requirements to become an MTN intermediary on data, I’m working on building a VTU app and i intend to buy my data and airtime directly from MTN...