if your payment is going to span from whichever date you start to the date you finish as it sort of does, then put up a calender where even if you missed your due date, you can put in the new date, especially when you want to change the plan, I know they dont change the plan when you are late, I just discovered that, but you should change that, because my bank statement shows money due, when all I wanted to do was put money on this month, but guess what, my phone is not even working, Not everybody has money at the same time each month.