I have been using Mcent for the past 1 year and I must say that it provides free recharge. I have earned about 500Rs from here.
But everything is not perfect about Mcent. Sometimes you install apps and you wont get the money. Those are the times when you can get really irritated by it. Most of my money I have earned through friend referral. That part has worked well for me.
But since the past few days the money offered to try the apps have become very low and not many new offers are coming. Also for daily rewards you will have to install 1 app after every 4 to 5 days. If you are using a new android phone, then go for this app and you can earn talktime from the apps which you will require.