What to do with a wall dispute among the neighbors?

Hi all, plot next to us was vacant and is being constructed now. This plot is in middle of our lane. We got our plot measured and we were well within our limit. If this wall is considered as common wall then our plot area falls short. The guy who's doing construction in adjacent plot is getting rude, aggressive and creating a scene. He is adamant that it's a common wall and he'll use it. The wall in question is a 4.5 inch wall and we have 9 inch pillars in our home. If he makes 3 inch puncture in wall as well as our pillars, it'll damage the wall completely and weaken our pillars also in a big way. He'll make punctures at multiples places for lenter, electrical and water fittings. It'll actually compromise our entire structures strength but he's not ready to listen at all. He's offering money for using the wall but we've told him that we don't need your money and want you to make your own wall. Please advise course of action if he forcibly punctures our wall. Thank you.