Dear Maxime,
As we said before “1) Our plugin works based on Woocommerce and based on Woocommerce, the total price of the quantity will show in the cart page. In product details, it only shows unite price based on the Woocommerce system.” In this issue, you could check out the Woocommerce default system as a reference.
Moreover, please provide the URL to check out the responsive issue to assist.
Best Regards,
ThemeLooks Support Team