post https://api.convictional.com/buyer/orders//seller-orders//refunds
Use this endpoint to add a refund to an existing order. This will add a new entry to the refunds array on the
order object. If cancelUnfulfilled is set to true, then any item that is being refunded and is not already shipped
will be cancelled as well as refunded. **Note that this endpoint does not currently handle return shipping or refund
payout