Neighbor's and their dogs

I don't have a problem with dogs, I have a problem with the owners who do not know how to control their pets. I have told my neighbors many times (lost count) to keep their dogs off my property; and their dogs still come to my property, most of the times to either poop or urinate. I come outside to confront them and they turn around as if they didn't see me. Their property is enormous, and never do they let their dogs poop or urinate on their own property, it's like they have trained their dogs to do it on mine. They never apologize when this happens either, it's like they could care less. I came out the shower one time with a towel on only, and to my surprise, the neighbor and his dog was directly outside my window, ON my property. I was in shock and now I am traumatized permanently. I don't need some creep looking at me coming outside my shower, or his dog pooping and urinating on it either. What can be done about this?