MTN Nigeria Just Posted This on their Facebook Fanpage:
You can only use your WOW bonus after you have used up your WOW main. Only WoW bonus expiresdaily at 11:59pm."
Meaning That you Get 200% of all your Recharges by dailing *885*pin# from 12:30am to 5:00pm and from 10:00pm to 11:59pm through out the week from Monday to Sunday.
NOTE: You can only Use your Bonus after you have exhausted the main Money you recharged and your bonus will expire same day by 11:59pm
What are you waiting for? Why not start dailing and enjoy your Bonuses?