how can I used the borrowed airtime to buy data

The MTN app is saying I don’t have enough airtime to subscribe whereas I have

Am mrs ogechi, I want to activate using 121 to buy data, I was using it before but I noticed that I can’t use it again, I don’t know why, it’s always show error, I don’t know...

Yesterday Afternoon around 2:32 Pm, I tried using my MTN app to purchase, 2.5Gb+2.5Gb bonus worth of #500 using my debit card to pay. I was debited but I didn't receive the...

Which other code Can I use to buy data cheap aside from *121#