Perform an Adyen authorization adjustment to modify a hotel or car rental hold after check-in

Steps

1. Obtain the original authorization's PSP reference after the initial check-in or rental hold is created.
2. Send a technical adjustment request to the Adyen Modifications API using the original PSP reference, providing the new amount that reflects the updated estimated total.
3. Specify the adjustment type as 'authorisationAdjustment' (not a capture or cancel); the network-level behavior is an incremental auth or auth reversal depending on whether the amount increases or decreases.
4. Await the modification result asynchronously via webhook; the webhook contains whether the adjustment was accepted or refused by the issuer.
5. If the adjustment is refused (issuer does not support the operation for that card type), decide whether to re-authorize for the full estimated amount or proceed with the original authorization and capture within its limits.
6. At checkout, capture the final settled amount using a standard capture modification against the original (or adjusted) authorization.