Add Proration Mode That Resets Billing Cycle with Fair Credit Adjustment

We need a proration mode that resets the billing cycle to today while also giving credit for the unused time on the previous plan.

Currently, the available options either:

• Provide credit but keep the existing billing cycle, or
• Reset the billing cycle without applying any credit

We’re requesting a mode that does both , so billing cycles stay clean and aligned with plan changes, while still being fair to customers.