GMO (fincode) does not support a dedicated API for partial refunds.
When a partial refund is required after a reservation is modified, GMO (fincode) updates the original payment amount instead of processing a separate refund.
Important
A partial refund requires the card issuer to re-authorize the updated payment amount. If the authorization is declined (for example, due to insufficient available credit), the refund cannot be completed.
Example
Original payment: ¥164,340
Updated reservation total: ¥153,340
Instead of refunding ¥11,000, GMO (fincode) changes the payment amount from ¥164,340 to ¥153,340.
Possible Error
You may see an error such as:
The payment could not be completed because the card's credit limit has been exceeded.
This is caused by the GMO (fincode) payment process and the card issuer's authorization. It is not an AirHost ONE issue.
What to Do
Try the refund again after the card's available credit has been restored.
If the issue persists, ask the guest to contact their card issuer.
If the refund is urgent, consider using another refund method, such as a bank transfer.