Been trying for weeks. I could not subscribe to mobile internet via "100#.
Number is in active period.
Balance is enough.

Kept getting:
Yr request failed due to technical issues. Try again later or call 123 for assistance.

Please advise.

Anything under "2 Mobile Internet" in *100# doesn't work.
But "3 Monster Bytes Promo" does work, however I don't need that much quota, I just need longer pass period.

I had not tried the Red App, but I will do try it once my current 1-day Monster Bytes expires.