Credit or revoke their balance

Move store credit on the named customer, from your own backend: grant when they paid you, revoke for a refund on your side or a correction. Amounts are whole cents at your retail prices; one movement is at most $5,000. Send your own request_id for every movement (your payment id, your refund id): a repeat with the same id answers 409 already_applied instead of moving the credit twice, so a retry is always safe. A revoke larger than what is left is refused (revoke_exceeds_credit) and names the remaining figure. Requires the X-Reseller-Customer-Id header.