Looks you're gonna be , at ME! Sorry, but I didn't bother to check the picture in your first post, my bad.

Before your situation gets completely out of control you've got to get your ML into the hands of someone who knows WTF they're doing!

I see stuff like this almost every day. In most cases it's no big deal, but matters are made worse when a well meaning shop mis-diagnoses a problem, then botches the repair work. Not only will you have the original problem to deal with but a man-made problem as well.

Replacing the gear selector switch isn't hard to do, but it's not hard to screw up either. I'm not saying that this is what happened, but before you go any further I'd recommend re-checking the switch installation. If your ML were in my shop this is the first thing I would do.