I’ve never dealt with Fox for such issues, so this post is perhaps a little unhelpful, however I can say that when dealing with Madison over a similar issue (new shorts, rapid wear rate at a seam) I was told it was usual wear and tear.
I fully understand the concept of wear and tear, but I expect (like you) for any clothing that costs that kind of money to last more than 30 bloody days.
I now avoid Madison shorts (shame as I love their jackets) and tend to wear Endura Humvee’s and some Fox stuff, both of which seem to last for 6 months hard use before giving in.