I know there have been lots of topics like this but I couldn't find a satisfactory answer in any of them. If I bought the 250mb plan for $15, and am going through the data very quickly, can I upgrade to 2gb for just $10 more or do I have to pay the full $25? When I go to my account view the only options are to add 250mb or 2gb, it sucks if that means I have to pay $25 two days after I bought the 250mb plan...