If a customer requires a refund, you will need to manage this via Catch.

The process is outlined in this FAQ: How to issue a refund

If you cancel an order or mark it as refunded in your eCommerce system, the status of the order will also update in Omnivore but it will not process any refunds and it will not update the order within Catch.

How to mark the order as 'Refunded' in Omnivore

Open Omnivore

Go to 'Orders' in the left-hand navigation

Find the order and click through to the page which holds all the order information

Click 'Mark as refunded'