This is the latest MTN plan called Quick WinD so when you have N100 on your mtn sim, you are free to do it. I don't think it selects sim so I will be dropping the code below of how to do the quick winD plan.
How to so the Quick WinD plan: N100 For 500mb
Go to your dial pad and dial *446*11*4*7*5# then you will receive a message immediately you dialed the code saying "Y'ello, your subscription to Quick WinD 500MB(N100) was successful.".
Note: it works on all browser and apps and even on PC/laptop so start blazing with it now because us the latest cheapest data plan.
So tell me in the comment box, if it work for you or not let me help you with the right solution to make this blaze on your device/phone.