A month ago, the corner of my 4G Lexar SDHC card broke, rendering it unusable in my camera. I wasn't doing anything unusual with it, it just broke off when I pulled it out of the card reader. I sent it in to Lexar for warranty replacement; I finally got the replacement back today.
I sent them a 4G Platinum II 60X card. They sent me back a Ritz-branded 4G Class 2 card. What's the difference? A 60X card is about 4.5 times faster than a Class 2 card.
Most companies, if they are unable to send the same item, will give you a free upgrade. I sent Lexar a fairly high end card, and they sent me back the cheapest thing in their entire line.