How can i change my data to airtime

Xtra special data of 4.5gb + 1500 talk airtime and i was not credited but debited my airtime of #1500

If I buy data from my bank instead of it entering as data it will enter as airtime how will I stop it

I borrowed #7500 worth of airtime from MTN yesterday and I paid back today but the borrowed airtime is not in my account. And while I tried to buy data plan with it yesterday...

I mistakenly buy 35000 data how can I convert my data to cash?