I have an attached house. My neighbor built an illegal attachment in the back before we bought the house and the roof of this attachment is encroaching upon my property. It was not reflected on my survey and is not mentioned in the title insurance. I need to do renovations to my property and I am restricted as this overhang prevents me from putting the wall.
I spoke w/the neighbors, but they don't want to do anything. Can I just hire contractors and ask them to remove the overhang when they work on my project? I guess not. How can I make my neigbor remove the overhang? They don't have a Certificate of Occupancy for the property after they illegaly converted it into a 2-family home and are renting out two floors, including the illegal renting of the basement. I just want them to remove the overhang so that I could go on with my remodeling project. Any advice is appreciated.

Go ask them nicely. If not, you can always report them to the local zoning officials.

I asked them nicely and you cannot imagine what happened - I can't even write here - it would be a nice story for the Simpsons show or smth. like that. They don't want to do anything.

Report them to the zoning officials and explain that you need their illegal work gone to do your lawful repairs and remodeling. If you make a complaint, they should send someone out to investigate and if warranted, initiate action against them to remove the violation or face o ther legal actions.