Months ago, my neighbour set up some stubs around their lot preparing fence. We measured it and found that it wasn't right - they took more space from us, according to the survey.

Today I talked to them and found out that they gonna build the fence tomorrow morning.
They insisted that what they did was right. In fact, while I was talking to them, the man was actually moving the stubs towards my lot side, just right in front of my eyes.

I would like your advice and help on how to proceed from here, especially what I can do when they have the workers here to start to build the fence tomorrow. I understand that if they did wrong, then they have to correct it later in which case it would cost them more money. I hope that we can solve this problem at this stage because after all we are neighbours. I hate to see that I have to get court orders for them to re-do their fence.

Thanks a lot in advance.