I've dealt with several manufacturing firms over my 50+ years on this marble and one thing you can count on is companies that supply you with materials will go with the cheapest seller of those materials, within reason.
When N first had the hinge breakages I said it must be the way people are handling things, even though I treated mine like a fine china doll. Suddenly my hinge broke also. In the same place every one elses was breaking (Hint #1) After several calls I got N to admit they had problems with the plastic quality on some of the manufacturing runs, which resulted in poor integrity of many shells. The Lesson? It wasn't really N's fault, not their intention and was readily replaced (On several ds lites.... FREE, postage & repairs. AND they added extended warrantee to those USED DS LITE UNITS. So I can't complain and am now understanding when a company appears to sell 'shoddy' materials.
Just write to them.
I have every cart I've ever bought from every company to this date, R4's (originals, & fakes, R4's. Acekards, SC & SC Mini's etc.. every version etc.. with packages) although the DS 2 isn't the best materials, they are the best product for me (running proper homebrew (read= not pirated or commercial), email retriever and paid (IGN) game guides on the go. My original use of one was to be able to store my hard copy collectors game guides for later value, sale and collection/value) which get readily destroyed in the humid climate which I live.
If you haven't figured it out, I have this fanaticism about having all the original artwork, cases, books, guides, instruction manuals etc, which is why I bought every game instead of pirating, it was not out of any sense of guilt or such... Heck, I'm still buying them to this date as each drops below a ten spot.
Anyway, I digress, they all have different quality but most will last if you treat them well. Inserting and removing them can be damaging in itself, which is why 1 of my DSi's is now nothing more than an elaborate eguide on the go, never removing it, it's now glued in for good.