Booking problem

Hi,

iv got a little problem with the bookingplugin. I use the the Impreza.

The bookingsystem considers that a week has 6 days. Where can I change it in 7 days?
Here an example of the page. https://www.localouis.be/wordpress/produit/barres-de-toit-voiture-goodyear-1-20-m/

Do you have an idea here I can change it?

Thanks a lot