Charges a card the customer has already saved. There's no payment form: BillPro charges the card straight away. The card also becomes the order's card.

Set operation to choose what to charge:

• initial_payment: the order's first payment. Use it on an order whose status is draft, pending or rejected. If the order has nothing to collect up front, the card is saved on the order and nothing is charged: payment is null and the order becomes registered.
• recover_failed_payments: every payment that's due and unpaid. That's each scheduled payment that failed, was rejected, or passed its date without being collected. They're merged into one payment for the total and charged now.

A declined card returns 200 with result.successful: false, not an error. message says why.