Private School Drop Out

Just had an unpleasant conversation with a bratty 9th grader who transferred to public school after attending the hoity toity private school in town. I'm shaking and I don't know why. He expects me to give him full credit for his half-assed effort. He didn't bother to follow directions on an assignment he's known about since the day he transferred into my class OVER A MONTH AGO - He transferred into my class the second day of school, so it's not like he's brand new to my class. Anyway, because he didn't follow directions I would not accept his work. He was dumbfounded. I highly doubt that anyone ever held the privileged little punk accountable. Along with directions-not-followed-assignment was a note from his mommy telling me that they didn't have time to get his assignment done the way it was supposed to be done, and would I please call her if it was a problem.
So I called and left a message on her voice mail (cell phone?) and I'm dreading the pending phone call - I will be trying to stand my ground and she will be trying to enable her spoiled brat kid. Why oh why did I become a teacher?