Elite Trades Sold me a non-genuine copy of Windows 7 Pro 64 bit O/S Unknown Internet

On July 6th. 2015, I bought a copy of Windows 7 Professional 64 bit O/S from a company called Elite Trades through Amazon.com. I spent nearly a year, and $1500 buying components one at a time to build my new computer because I am retired and live on a fixed income. I bought my last component on Oct.2nd and it arrived around Oct. 10th. I spent about two days buiding the computer. After I got the computer up and running, I installed the O/S. On Oct. 28th. I decided to upgrade to Windows 10 Professional 64 bit to see if I liked it better than Windows 7. It was then that I was informed by Microsoft that my copy of Windows 7 was not genuine and I could not upgrade for free. It would cost me around $200 to buy a Product Key for the upgrade. I immediately sent an Email to Elite Trades. Elite Trades has never even acknowledged receiving my Email. I called Amazon.com on the phone to register a complaint about the seller on Nov. 1st. They informed me they would contact the seller and let me know what could be done. As yet I have heard nothing from either Elite Trades or Amazon.com.