Amazon - What Is The Benefit of Purchasing through Their Marketplace for Buyers?

I am being genuine when I ask what is the benefit for purchasers when buying through the Amazon marketplace?

I have had 2 attempts at purchasing through Amazon.com.au, purchasing hard drives that are fulfilled through their market place. The first, the seller did not honor the price.

The second (different seller), no product arrived 6 weeks later. No communication or response from the seller at all. I was charged successfully though. The tracking number they supplied is not even valid.

When I have made contact with Amazon support, it is like chatting with a bot. No intelligence displayed, repetitive, and ultimately, no solution.

You would think that there would be some guarantee or assurance from a multi-billion dollar company such as Amazon, but as far as I can tell there is nothing of the sort.

Now, I can easily just go to the credit card company and cancel the payment, but after waiting this long, and missing opportunities to purchase these hard drives elsewhere, I would like the solution of getting the products ordered at the offered price.

Yesteday when I was in contact with them, I asked to have the matter escalated to a supervisor, and they came back and said they could not do this due to technical difficulties. How convenient.