Sounds like you are afraid of confrontation. In order to get this issue solved, you need to get over that fear first. Then you mark your driveway and tow the car every time it is blocking you. Unfortunately, some people take your whole arm when you offer them a hand. I had a similar issue a while back. One of our neighbors would work on his car in MY driveway lol. The driveway has gates but i would leave it open because I was to lazy to open and close it every time i moved my car lol He would do it while i was at work so we never noticed. We only found out when my wife stopped working (due to the birth of our daughter) and caught him. I tried being nice about it but he pretty much told me to go F myself since he felt he can use it since no one was home. So after that i always shut the gate. People will walk over you if you let them.