Hello there, I just accidentally purchased a limited weapon on Zombie Slayer. I meant to click on the "social feed" tab on the home page, but as I scrolled I guess that I overshot. I was just wondering if I could return the item and get any UN credits back, as with regular items (that are bought with in-game cash).
This would most certainly be one of those types of issues, send them a message explaining what happened and that you would like to have your accidentally bought item refunded for the UN that you paid. That link was at the top left of the external game, not sure where it is in the original FB canvas game but it's there somewhere i'm just not there to find it.
Send a message into support explaining your situation and make sure you include your account information.