There might be some discrepancy between 'renewal date' and 'billing day'. I think I remember that they do billing 2 days before monthly renewal date- possibly so there's time to address the need to update a payment source before service gets cut off.
"When will my Auto Renew Payment be deducted?
Your monthly plan payment will occur two days before the last day of your current billing cycle. Your billing cycle will still continue for the full 30 days. If you have any available rewards, those rewards will be applied to your account first. If a balance is due after all available rewards have been applied, any remaining balance will be charged to your credit/debit card on file. If you have more rewards points than necessary, those points will remain on your account and will be used towards next month's cost."