Just select O2's Big Bundle to recharge the appropriate amount every month, and they will exchange the appropriate credit limit for your minute, text and data allowance. If you have enough credit, the Big Bundle will last for one month and will automatically renew on the same day of each month. If you do not do this, you will be charged at their standard rate for the gift package until all your credit is gone. When you top up enough points again, you will receive a bundled subsidy.