post https://paella-sandbox.billie.io/api/v1/order//confirm-payment
This endpoint needs to be called if a customer is accidentally paying the purchase amount
directly to the merchant. (See usage of virtual IBANs).
As a consequence of sending this call, Billie will make a direct debit from the merchant
or net it against the potential outstanding payout amount of the very day.
Please mind that the order state will only be updated after Billie actually receives
the money of the confirmed payment.