Ninty doesn't replace broken cracks, so find something else wrong with your system if you're that desperate over a small crack...
You got crack in your DS? You shouldn't be doing crack over your DS like that.
You should give Ninty a call. Last I ever heard, as long as it's still under warranty, they will fix it. It is a known defect in the lites.
When mine got the crack, I opened up the battery compartment, and put a slip of paper between the DS's contacts and the battery's. It worked for me, but I don't know if Ninty of Aus. handles things the same, that, and it was a long time ago.