Roger I understand your frustration but think about this...
The cost to maintain a phone/email staff to respond to warranty issues has a cost. That cost has to go into the price of the headlamps, the cost of the materials, or their profit margins. Think how many more customers would be affected if they raised the cost of their products or lowered the quality to be able to afford a heavily staffed warranty service department?
I would rather they keep their quality up, keep their prices down, and keep making money so they stay in business offering me a quality product at a competitive price rather than tote a large warranty department to solve problems. Possibly the lack of a warranty department is indicative of the low number of warranty requests they receive.
Also it's a $25 dollar headlamp. If they paid someone $12 an hour to handle your problem for say 1/2 an hour costs them $6 plus send you a part, postage, etc they might spend $10-$12 repairing your $25 headlamp that they made $10 selling to you. Now they have lost money keeping you happy. Plus maybe 50% or more of the people that crack their headlamp will just go and buy another headlamp, maybe another Petzl, now they have made another sale.
In modern day retailing it just does not pay to cater to everyone's cracks and issues. All of that has been cut out of the cost as the cost of the products has been driven down over time, the whole Wal-Mart effect...we want it faster, cheaper, not necessarily better.
I would argue that if you bought say a $100 Strikeforce headlamp you probably would have gotten a warm body on the phone and a replacement part. For a $25 plastic (made in China?) headlamp there just is no margin for it.