With the success of Amazon selling online through their marketplace, they opened up the market place to allow third-party vendors to sell as well. DO NOT purchase items which are not sold and fulfilled by Amazon!
When it comes down to issues with the third-party vendors, they do not have the power to force the vendors to respond to you or to do anything about complaints.
I am an Amazon Prime member and just one bad third party transaction reversed years and years of "savings" realized by buying from Amazon.
DO NOT BUY from Non-Amazon vendors in the Amazon Market Place! Buyer Beware!!!