I'm writing on behalf of my girlfriend. She insist that Amazon's customer service is the best she's ever had. She ordered some books for school. A week and a half later, the post office's tracking system said it was delivered. She called the post office and they insisted that it was delivered (because the computer said so) and there was nothing they could do because it wasn't insured.
She then visited Amazon's website to look for their customer support number but instead found a system that asked for her phone number and a time when a support rep should call her. She submitted her info and within a few minutes got a call from a rep. It's nice not having to listen to hold music while waiting to speak to a person. In addition, the rep already knew the details of my girlfriend's account so there was no time wasted in verifying her identity and what she ordered.
My girlfriend told the rep her situation. The rep apologized and immediately started the process of shipping another set of books to her via express method. That's all there was too it. Friendly and efficient. Also noteworthy is that the rep was located in the US and spoke perfect English.