PhotoBiz allows you to accept credit/debit card payments for your Client Galleries, Scheduling, Invoicing, Forms, and ECommerce. If you need to process a refund to your customer for a credit or debit card payment, you'll need to log into your merchant account that handled the transaction to issue the refund.
Here are some helpful links to the merchants that can be used to accept Form payments with PhotoBiz ECommerce:
Processing a Refund With Stripe
Processing a Refund With Square
Processing a Refund With Paypal
Processing a Refund with Authorize.net
Processing a Refund with PayJunction
Processing a Refund with iTransact
Please Note: For account-specific questions with your merchant, you'll want to contact their support as PhotoBiz Support has no access to that information.