Offerwall issues

So tired of trying offerwall games and getting screwed by them. One I did ended up not crediting after so many levels but my mom had no issues. Now my cousin tried and opened the game as soon as it downloaded and it won't register as downloaded so she can't play it now. Then I downloaded one and it showed it worked so I played 10 levels and waited for the credit. But it says I played 7. So I played to level 14 and it says 7. How does it register 7 levels and then just stop when I played 10 all at once?? So that was a waste. We download the game and open immediately from Google play, play for several minutes and check the offerwall. Internet is fine. What's the problem?