Zombie Brand is still available to me despite refunding. Also, I used it in a custom game to see if it was actually available and it crashed the game hard.

Steps to Reproduce:

Logged into the Game Client
Clicked on "Play Game."
Created a custom game with only beginner bots on summoner's rift
Selected Brand
Zombie Brand skin was selected by default
Began game using skin with Leona bot (two on each team)
Neither Leona nor I load, I have no money to start with, and the game proceeds spawning minions while I can't move from the fountain.

Screens:

http://i.imgur.com/jmk5y.png
http://i.imgur.com/BnG0l.jpg
http://i.imgur.com/QgdQI.jpg
http://i.imgur.com/WjCC0.jpg

i still own the skin after refunding it too