I did end up getting Amazon to call me. They were very responsive and called back within minutes of me placing the call request. However, the registration issue couldn't be resolved so I returned my Kindle to the store where I purchased it. The replacement unit works just fine and my wife is now happily buying books with her new Kindle
Amazon's call back support was very good. They were quick to respond, friendly and thorough. They offered to send me a replacement directly if I preferred, or if I had trouble with the local store where I made the purchase. They did a great job of ensuring that what could have been a bad experience turned out well in the end.