How to contact customer support

I just bought a new Dell laptop (XPS 15 9500) (directly from Dell France). Unfortunately the trackpad is not functioning correctly. It often misses left and right button mouse clicks. I tried to contact support but it says that my service tag is invalid (even when detected automatically). Now I find it impossible to contact Dell. The only phone number provided seems to be an American one which I can't call here from France. I can't seem to find any functioning email address to make contact.