Why can't I use my Data bonus 08146227072

Please how can I change my bonus to my main data plans how can I use my data plans

I Subscribed for 600 Naira 1GB data and I was given a bonus only to find out I can't use it after my normal data was exhausted. Please kindly help me to solve this b4 it expires.

MTN data bonus unused

Why can’t I use my data bonus by midnight or morning