Please update the theme to the latest version and Woocommerce as well.
Before update delete “woocommerce” folder in the directory wp-content/themes/legenda/ and it’ll be reuploaded from a new theme package.
Also update all required plugins http://www.8theme.com/download-plugins/ .
Don’t forget to create back up of your files and database before starting update process!
It is apparently only happening in Internet Explorer. I did try myself in Internet Explorer and and I placed an order 3 times on each site. Only once out of 3 times it did hang when I clicked “place order” with the credit card payment option