Blizzard encountered some issues affecting the Trading Post refund process. As a result, all item purchases are temporarily non-refundable.

(Source)

Due to some issues that are affecting the refund process, the ability to refund any items purchased from the Trading Post 36 has temporarily been disabled. The Customer Support Team will not be able to assist with refunds while these issues are active. Updates will be posted once this situation is resolved.

Updates will be posted once this situation is resolved and we expect all applicable Trading Post item purchases to be refundable at that time, including items purchased during the nonrefundable period.

Thank you for your patience.