If you have Stripe integrated you can refund the guest a former Stripe charge directly from the booking in Sirvoy instead of manage the refunds from the Stripe account dashboard.
You'll find a red "arrow icon", se below, at the same row as the stripe payment in the Sirvoy booking. Click on the red arrow and add the amount to refund.
A refund with Stripe takes about one week. A new row with the refund will appear after a while. When you create a invoice both the charge and the refund will follow along to the invoice.