Jewelry Unlimited off of eBay Fake jewelry don't buy Atlanta Georgia

I received my wedding band that I ordered from jewelry unlimited on ebay it was suppose to be 10kt yellow gold with diamonds in the mail a couple of days ago. When I opened the box it looked ok until I took it out. I noticed it felt like plastic I thought nothing about it until I wore it on the second day I noticed a diamond had already fell out.  So we took it to a gold place where they told us it was not 10kt gold & if we paid that much we got scanned. So Now we're trying to figure out what to do & how can we get our money back. Very disappointed in jewelry unlimited on ebay even worse out of a wedding ring.