I want to change my plan and I was looking at the different plans. There are two plans for $40 each. Everything is the same on those plans except one has 5GB of data and the other has 15GB. Everything else seems the same. Why should someone pays $40 and choose 5GB instead of 15? Or the other plan that cost $50 and has 8GB and everything else is the same as the $40 plan with 15GB. I am confused.