In the U.S. you can't e-mail support. But you can call them at 1-800-APLCARE. They are available 7 days a week. Yes an Apple Store is a good bet. Some things to note about these adapters:
1. You can't pull them by the cord. This may cause fraying.
2. You shouldn't wrap the cable around the brick, as the cable bending at the brick can bend and fray.
3. Don't let the cable bend more than 10 degrees at any joint
4. Use the grounded connector (third prong) with a properly grounded outlet when connecting. Any hardware store will sell you a ground tester plug to make sure your outlet is properly connected.
5. There is a clear plastic wrapping on some of the bricks which is best if removed.
6. Pack the power brick cable in a zip lock bag to make sure no foreign elements get in the connector while in the bag.
Look at this article to make sure you aren't putting it on surfaces which might cause the machine to overheat:
http://docs.info.apple.com/article.html?artnum=30612
And run the hardware test that came with the machine to see if it detects anything wrong:
http://docs.info.apple.com/article.html?artnum=303081