I tried to buy a textbook for class on Amazon.com from an Amazon seller. After emailing the seller a week or so after buying the book, I got an email issuing me a refund. When I inquired further, I was told that the seller didn't actually have the book in stock.
This is bad because:
I need the book now, since class has already started.
I am not sure if this seller would have refunded my money if I didn't ask about the book.
I am glad I emailed the seller, because if I hadn't, I could have ended up just waiting for the book and never receiving it.
I ended up having to buy a new book at almost twice the cost, but at least I was able to get expedited shipping, so it should arrive shortly and I can do most of my work for class.