Board Thread:Shadow Fight 2 Discussion/@comment-27313994-20160309004937/@comment-25669516-20160309194842

Their official support site is support.nekki.com

However I had trouble accessing it. If it works for you then great, if not then you can fill out a request ticket on their automated ticket system here:

https://nekkisupport.zendesk.com/anonymous_requests

Under project select Mobile game> shadow fight 2> iOS and fill out the form. Do mention your email and Gamecenter ID in the description!