When someone takes your business and makes it their own

How do you react? What is the best way to protect own interest? I wanted to put this in general discussion because i think socionics has something to do with this, or ways of dealing with it might be socionics related. Last but not least, are there any types more likely to do this?

Basically i've come across something like this at work a couple of times right now and it's enough to have me concerned. Thanks