I was looking forward to the new wing but I'm glad I checked the forums first. There is currently an issue with unlocking at both the NA and Europe servers. Many people have reported buying with gold but not getting the wing unlocked.
Blizzard's Official Sticky-ed Forum Post on the matter
Reddit post: Lost 700g plague wing still locked
Reddit post: Gold Glitch is happening on NA, watch out.
Update#1: Latest Blizzard thread: Known Purchase Issues with Plague Quarter - 07/30. The thread has 121 pages with a lot of failed purchase posts at this time of writing!
I guess I'll hold off on unlocking first... Update#2 (31/07/2014 02:00pm GMT): I just managed to unlock it with gold without any problems.
