Funny, reading the two posts above mine.
Amazon's customer service is THE WORST. It always takes them two or three tries to get it right.
On the other hand, GoHastings customer service is seriously the best on the net. They have absolutely no quality control over their used DVDs, so I tend to get a lot of duds from them. But every time I've had to contact them for a defective DVD, their service has been quick, kind, and completely hassle-free.