Update cart page forbidden

-- url of the page with the problem -- : geraldinemaurin.com/commande-cd
-- HikaShop version -- : 3.0.1
-- Joomla version -- : 2.5.28
-- PHP version -- : 5.5.38
-- Browser(s) name and version -- : Firefox v52

Hi everyone!
I'm a new user to HikaShop, but i know very well joomla.

I have a J3 website here : geraldinemaurin.com/commande-cd/
I just wanted to sell 1 product. But i'm not sure i properly configured my HikaShop. When i click on "add to cart" button i have this message:

You don't have permission to access /commande-cd/product/updatecart on this server.

I didn't success to add a price on my product neither. Do you think these two elements are connected?
Thank you very much for your help!
Regards

Miran

Just started to receive the same problem here - www.acrespetproducts.com - when adding an item to the shopping cart.

Any resolution?

For anyone experiencing this issue get in touch with your hosting provider.

Our hosts response which corrected the issue:

"This issue should be solved. The error was getting triggered by Mod Security"