Schedule a plan change with proration
Schedules a plan upgrade or downgrade for an order with automatic proration calculation. Credits are applied for the unused portion of the current billing period.
Bearer authentication of the form Bearer <token>, where token is your auth token.
The order ID (can be internal ID or display ID)
The current version of the order (for optimistic locking)
The date when the plan change should take effect (ISO 8601 format)