Cart not update

[UNIsetENVATO]

Hi, i’ve installed UNICON theme (v. 2.2.2) and woocommerce on http://www.unisetcompany.com
I’m trying to buy (as demo) a free product i’ve put on the shop, but if i click on “add to cart” and then go to my cart, the cart is empty.
If i wait more or less 10 minutes, the cart refresh and display the item. But if i change the quantity (from 1 to 5) and click un “update cart”, the cart returns to the previous set (1 item only selected).
How can i fix that? It seems there is some trouble with the updating fuction of the cart.
I’ve read in a previous ticket of 4 months ago that the problem was that the theme was not up to date, and for this reason i update to the last version. But problem still remains… i’ve also disable all extra-plugins.
The shop: http://www.unisetcompany.com/shop
Thank you in advance,

Lorenzo C.

Ticket