Partial refunds can be done through the QuickPay Manager. When logging into the manager, navigate to Payments and find the payment you wish to refund. If refunding from the payment overview, click the refund icon to the right of the payment.
This opens an overlay with 2 options: “Full refund” and “Partial refund”, select partial refund, now you will be able to change the amount you wish to refund.
Your Anyday ordres can also be refunded partially depending on how it's integrated on your website, either directly on your site (Magento and WooCommerce) or through Quickpay, it can be done in both places.
See video guide below: