If you are logged into your spanx.com account, you can check your return status in "My Account". Click on "My Returns" in the left panel and you will see a list of started and completed returns.
If your return is in transit to us and you would like to track your return package, simply reference the tracking number that was sent to you via e-mail on the shipping label. Use that tracking number to track the shipment online here: https://www.fedex.com/en-us/home.html.
Once your package shows as "delivered" you can expect to receive your refund within 3-5 business days.