MCent — Not recieving airtime and referral cash

Website: www.mcent.com

I installed this app with a sole reason to earn free talktime as promised by this company. My mobile number registered in mcent is *****45112. I have referred many of my friends to download this app and they did and I received airtime for referring most of them except three people in the app it shows the status of the referral and according to the terms the referred person has to download an app from mcent for me to get airtime and the three of my friends have done this. But still I haven't got the airtime.