My Single Mom Life

I need a new battery for my phone, so I went to Amazon to buy one. They have third party sellers, merchants they call them, that they allow to sell items basically under the Amazon name and website.
Amazon does not sell this battery themselves, I had to purchase it from the merchant.
I found the battery I needed, the cost was $9.95. It weighs about 6 ounces at most.
I checked out, and they charged me $15.49 for shipping and handling!
I know they jacked up that price because if you look at their shipping and handling prices, there is no way in hell I should have been charged that much. It should have been $8-$9 at the most for standard shipping right?

I cancelled the order immediately after I saw that, and then sent them an email asking why it was so much. They still haven't replied.
I sent Amazon an email too asking why they allow merchants to jack up shipping/handling when the sellers profiles clearly state different prices.
Amazon said that merchants have to abide by the prices they have set forth in their profiles and they would look into this particular sale and charges.
It burns my ass.
Yes, what I purchased was a small sale, just 1 item, but that doesn't give them the right to raise the shipping cost to make a bigger profit.

I ordered some other things from Amazon the same day, and 1 was an item from another merchant, just 1 item again, much bigger, much more pricey, and they stuck by their shipping and handling prices they have on their sellers profile. The item was well over 5lbs and cost me $27.83, and they only charged me $8.00 to ship by FedEx.
This clearly tells me that the first seller was jacking the price up to make a larger profit.

I've seen this happen on Ebay before. The seller states one price in the sale, and then changes the shipping at checkout because your winning bid was clearly lower than they wanted to sell for, so they want to try and make up that lost money.
It's not right and it pisses me off.