Im just a newby here and reading up on all of the horror stories, getting ready for the unexpected, like this one. So sorry to hear about the problem, but thank you for sharing. On a side note, if the manufacturer does not fix it for you, and you need help plastic welding it, let me know, as I can provide lots of tips.

I plastic weld personal motorcycle fairings for repair, and they turn out strong and solid as ever. The key is just to make sure you dont overheat the plastic, making it too brittle, and to do a zipper style weld which will insure that it will hold. That section would definately need more on the insideof the yak, a thicker layer that is, in order to handle the stress and pressure causing it to flex. Believe it or not, a large saudering iron can weld just fine.