How do you handle property boundary disputes with builders?

[Hemang S.]

We are in Chicago and the lot next to ours was just bought by a contractor/builder. He just finished demo-ing the old building and told me that our property encroaches on his (according to his survey) by 4 inches- the 4 inches are all sidewalk but would make the walkway on the side of our building narrow if taken away. The 4 inches were part of our property when we purchased it but our survey said there was a 2 inch encroachment. The builder said he is going to keep working unless he gets a legal notice from our lawyer.

I just saw that he actually already cut away some of the concrete side walk from our property and was shocked that he would keep building (and cut out part of our sidewalk) before the survey issue is figured out. I am wondering a few things:

1) What would you do in this situation? 

2) When the two surveys conflict, how do you get the builder to stop building so things can get figured out?

3) Any lawyer recommendations for this in Chicago?

4) Any other advice for me?

Thanks in advance!