Amazon DO have a dispute proceedure for MarketPlace Sellers
,I used it only recently.
You must send at least 3 emails to the seller,giving them time to respond,then if they don't go to the Your Account page,here you will see your order.
Click on the "File a Claim"page and leave it to Amazon to do the work for you.If they cannot get any joy from the seller they will refund you the cost of the item(inc postage)They did this for me with a DVD box set that never arrived.
If this isn't clear let me know.