So a couple weeks ago i was out retrieving a sled was a pretty cold day and the wind blew all day. When we finally got back to the truck at dark i go to open my bag and it is a little bit frozen, pull a little harder and the zipper rips off one side. So now my question is, is there a way to put the zipper back on so i dont have to get a new bag? Also, any advice so that this doesnt happen again?