I want to know why I was charged back to March 13 when I changed my plan on March 23. I can understand if you change in the middle of your billing period but if you look at my bill, I was then charged again for the full amount again?
On the March 13th bill you would have paid for your previous plan for the period from March 13-April 13. If you change your plan on March 23, you would then be credited for the portion of your old plan from March 23-April 13 and charged for your new plan from March 23-April 13. The prorated charges would appear on the April 13th bill.