How can I tame these kids with only 3 more months left and still get them to learn anything?

I have a first grade cl full of defiant, jaded students. When I first began teaching this cl, the students were out of control but I managed to tame them into a cl with only *minor*problems. Recently, two severely problematic kids were placed in my cl. I'm a first year teacher and it's been hard enough as it is! I've suspended recesses, given tons of positive reenforcement (privledges, prizes, praise, points, fun lessons, etc.). I've read Harry Wong and Fred Jones, etc. I don't know what else to do! When a kid talks back to me and tries to run out of the room, I send him to the princpal but he gets sent back. When I call the kid's mom to come sit with him, she generally says no. Yesterday a kid destroyed a book of mine and he got send back from the office. I have hardly any parental or admin. support! There are two months left of the school year. I've spent so much money, put in hours of time, etc. There are a few innocent little ones, but not enough! Help!