I have checked your site and single product page is ok.
We’ll release version 3.12 of our theme that should fix the problem with out of date files.
So, you need to wait for theme update then update the theme on your site.
Please, update theme to the version 3.12. It’s available on ThemeForest.
Do the backup of theme options before the update (Theme Options > Import/Export > Options > download .json file)
After update disable XStore Core plugin, re-activate theme, then activate XStore core plugin and go to Appearance > Install plugins > update Core plugin.
We have made some improvements for the cart/search/wishlist options in the header http://8theme.com/demo/xstore/update-history/ so, after update very likely you will need to choose the position of these options in theme settings.