I am so sick of my neighbors!

Ughh, I am so sick of my neighbors! They moved in a few months ago and I hadn't had any problems with them until about three weeks ago. Our driveways are right next to each other, I have a double wide driveway and they have a single wide driveway. One day I came home from work and there was a total of four cars there and I had to drive on my yard to get into my driveway because they had the end of it blocked. I didn't say anything to them that time since it was the first time. Then a few days later I came home to the same thing. So I went and knocked on their door and nicely asked that they move the vehicles and do not park in my driveway anymore. But it keeps happening. Last night I took out the garbage and saw that I was completely blocked in! I didn't do anything about it then I came home today for my lunch hour and could barely get into my driveway again. But I didn't want to deal with it on my lunch hour. Now, I just came home from work and I was not able to get into my driveway again. So, I went and knocked on the door and said they needed to move the cars and to please not park in my driveway anymore. She didn't say anything so I went back out and sat in my car on the street and waited ten minutes. Nobody came out so I went back to the door again and said I am waiting for you to move the cars so I can get into my driveway and she said "They will be leaving in about 20 minutes." By this time I was very pissed, and I said I am not waiting any longer either get them moved or I am calling the police. She said "fine, if you are going to be a b**ch about it." Can you believe that. Ughh, I just want to scream!