You can do a google search and see that others have had this issue. Or you could contact Uggs to see about replacing. A really good cobbler might be able to place some invisible stitches. Good luck.
Uggs are so hard. There is really no way to fix them so you can either call Uggs directly or maybe a really good cobbler can figure something out but you may loose part of the reason you love Uggs because they will become stiffer.