To contact a Seller about an existing order, click on the "Contact Seller" button to the right of the order in question from Buying section (Members Area > Buying):
HipStamp: https://www.hipstamp.com/members/buying/purchases
HipComic: https://www.hipcomic.com/members/buying/purchases
HipPostcard: https://www.hippostcard.com/members/buying/purchases
Once the Seller responds, we'll notify you via email that you have a new message, which you can view from the Members Area > Messages section:
HipStamp: https://www.hipstamp.com/members/messaging/browse/filter/received
HipComic: https://www.hipcomic.com/members/messaging/browse/filter/received
HipPostcard: https://www.hippostcard.com/messaging/browse/filter/received