When a charge is corrected.
Most of what would need a refund is never billed. What remains is corrected on the invoice it is on, or, for a payment made with the call, on the network it was made on.
Never billed
A call that produced no answer, an answer that found nothing, a withheld estimate and every refusal cost nothing, so none of them is on an invoice to be refunded, and a payment made with such a call is never sent.
What else a priced call is billed for is on terms.
What is corrected
A charge made in error: a call billed more than once under one idempotency key, a charge for a call the terms say is never billed, or a price other than the one the catalogue carried when the call was made.
A retry sent without a key and billed twice because its attempts fell either side of midnight UTC is a charge made in error too*.
A retry sent without a key under a new message id is a second call, and is billed as one.
A payment made with the call and taken in error: taken for a call whose answer was withheld or never delivered, taken twice for one call, or at a price other than the offer the call was answered with.
The credential walkthrough shows how to name a call with a key, so a retry of it is the same call.
How to ask
Write to support@citature.com from the account's address within 30 days of the invoice's date, naming the invoice and each call: the tool, the time, and its idempotency key or message id.
For a payment made with the call, write within 30 days of it, naming the transaction's hash from its Payment-Receipt or the ledger, the tool and the time. There is no account or invoice to name.
How it is corrected
An invoice not yet paid is reduced by a credit note before it is due. A paid invoice is refunded to the payment method it was paid with, or credited to the account's balance against its next invoice.
A payment made with the call is refunded in the stablecoin it was paid in, to the wallet that sent it.
What a delivered answer is billed for
Delivery, not a conclusion. An answer reporting what a record does not state, or a clause the record cannot settle, is the tool working as documented, and its charge stands.