Best thing for you to do is call them up and say, "I was a fool about my minutes and I owe you a bunch of money, but is there anything we can do about this?"
Ask about payment plans, and ask about paying for the highest monthly rate plan + overage for the months you went over. Be nice on the phone, but don't take no for an answer until you've talked to a customer service supervisor.
You've got nothing to lose by trying, and at the very least, even if they won't reduce the bill, you might get a little extra time to pay off the bill. The most important thing is that you don't let them send your bill to collections, because that will put a big black mark on your credit for the next seven years.
EDIT: It looks like you didn't even pay in full last month. What's up with that? They're not going to like that when you call about the current bill. Well, good luck!