Mobile menu: clickable items

Hi, I have an issue with the mobile navigation on http://www.ksmpatent.de/en/ If I view the webpage on my smartphone I can click on the menu icon to fold out the menue. As you can see, there are menu-items with sub- and subsub-menu-items. If I click on e.g. “Contact”, subpages fold out: I see “Our Office in Stuttgart”, “Our office in Reutlingen” and “Contact from”. Problem: i cannot click on “Contact” to see this page (because it has subpages) and I also cannot click on “Our Office in Stuttgart” (because it has subpages as well). Is there a workaround. I used other templates that provide a little arrow if the page has subpages. That enables me to decide if I click on the page itself or on the arrow icon to open the subpages. Can you help please??? Kind regards Alex