As I've said elsewhere on this website, the main affiliates sites I recommend purchasing from (Amazon, Adorama, B&H, J&R plus a few other stores) are all retailers that I actually use myself and all have good customer service in case of problems.
I recently placed an order with Amazon for several items (printer ink, paper, fluorescent light bulbs etc.) and one item arrived damaged. I had ordered a 6-pack of daylight balanced spiral fluorescent bulbs and when I opened the (undamaged) package I found one bulb broken. Not only that but one of the other five wouldn't light up at all. Bummer :-(
So I called Amazon and amazingly enough I was talking to a live human in under 20 seconds. She took all my information, looked up the items, checked on returns/refunds etc. then told me that she was shipping out a replacement at no cost (via overnight delivery) and that I should just keep the bulbs I had that worked and throw away the broken and malfunctioning bulbs (or otherwise dispose of them in an environmentally responsible way since fluorescent bulbs may contain mercury) . No fuss, no complaining, no extra charges. That's what good customer service is about and it's why I like Amazon.
So Amazon will remain on of the stores I recommend most. In all my years of dealing with them I've had very few problems, never any trouble with returns and always good customer service. One note though and that's I generally buy items sold (of at least fulfilled) by Amazon themselves, not 3rd party merchants selling independently though the Amazon website. That way if there's a problem you deal with Amazon, not with the 3rd party merchants.
Just in case you can't find it on their website (it's there but you have to look hard), the Amazon Toll Free Customer Service phone number is (800) 201-7575.