1. Go to Orders and click on See Details of an order which you want to refund.
2. Scroll to the bottom of the order page and click Request a Refund.
3. You will see this form:
4. Adjust it to indicate you refund just one item. You need to select from a drop down menu a reason ('Wrong qty received') and change Qty returned by customer and Qty you want to refund for to 1 (or other number if you refund for more products).
5. Click Submit button. Please be careful to do not double refund. After few days you may receive a return request from JET about this order (happens when a buyer claims a return even if you already refunded it). In this case you need to complete the return request which will come by inserting 0 for all the returned items. This way a return will be acknowledged, but not double refunded since you are right now already refunding it.