annoying neighbor,what to do?

we live at the end of the cul-du-sac, very nice except the next door neighbor take the cul-du-sac as they own it. They have a babysitter who keep parking her car by the curbs in front of my house. Her car's back is like a foot or so sticking out and sort blocking my drive way. By the way, my drive way is wide and takes 2 lanes. I know parking on public street is legal, and i am not sure that if i should make a big fuss abt her car blocking me by few inches. But its very annoying as there are lots of other place to park. If there an easy way to fend these people off? Thanks