Fake Yo-Yo Ma Autographs selling on Ebay

I recently purchased Yo-Yo Ma's picture with his autograph on it on Ebay. The seller was rated over 500+ with no negative feedbacks. I trusted his advertisement with his own Authenticity Guarantee when I made a decision to purchase. A few weeks later, I met a professor at Johns Hopkins University who worked with Yo-Yo Ma for many years at Aspen Music Festival, and who had Yo-Yo Ma's original autograph. I compared his with the one I purchased over Ebay, and they weren't even similar. There are hundreds of Yo-Yo Ma's autographs selling on Ebay price range from $30-300. I am going to submit a complaint at Ebay but I am not sure what they can do as there are so many sellers selling it, not just the one I purchased from. I was hoping there will be no more victims like me and therefore I am posting this information here.