What's the upgrading & downgrading policy?
For upgrades in plan level, you can choose to be charged the new rate immediately or on your next billing cycle. In the first situation, you will be charged the rate difference between the new plan and the old plan and you can enjoy the service of the new plan immediately. You will start paying the new amount for the upgraded plan the following month.
For any downgrades in plan level, the credit card that you provided will automatically be charged the new rate on your next billing cycle. You can enjoy the service of current plan until the next billing cycle.