Both, my experience and yours, shows that the only thing that makes them inclined to do anything is fear of negative feedback. But even then they are willing to do the absolute minimum. They are minimalists whose only aim is to hold on to your money. Feedback is a powerful tool to use when things go awry. Granted, not every negative feedback is meaningful and accurate. Anyone can give negative feedback even if they are wrong. In my opinion, it's important to maintain integrity of the feedback system.
You are frustrated, helpless and angry and want to lash back at them. In my case, in the end, I will get my two suitcases. I will actually end up with three, as Amazon sold me one, which was priced more than $100 higher, at a $70 discount. I have three suitcases at a slightly higher average cost then I had intended to spend. I can still return the the one Amazon.com sold me. I might keep it as the average price ($148) is still a lot better than the lowest market price of about $235.
I am leery of buying, used merchandise in particular, from e-bay, since a lot of stolen stuff ends up on e-bay.