Here is how to issue a refund to credit card where the batch has been already settled by merchant processing company.
Open trip, click Pay icon (or button), in payment list click the a transaction that you want to refund, then click the REFUND currently highlighted record.
If amount to refund is less than transaction amount in the highlighted record, enter in the Refund Amount field.
If you are refunding the full amount, just click REFUND currently highlighted record.
You may enter an optional Refund Reason text for your records.