ATRIUM Replacement Part

Made the mistake of using a small town general contractor to replace all our windows a few years back that is useless. We had what I refer to as a night lock that prevents the window from opening more than a couple of inches, break. It has taken me a year to get this far. A lady from Norandex that bought out the company the contractor bought the windows from told me from the window sticker they are made by Atrium and referred me to you. I need to find a replacement part but it has no part number of it. Do you know what the part number would be? I have added a picture of the broken part, where it broke out of, and what it is supposed to look like.