Amazon charging for video subscriptions I did not authorize Seattle WA

Amazon charged me for four video subscriptions that I didn't sign up for and didn't watch - Walter Presents, MHz, James Ellroy and Fan Go.  They ended up on my Amazon consumer credit card, which I promptly cancelled.  I have Netflix and streaming Direct TV which go through Roku and are charged to my bank account so how the heck did Amazon link these other streaming videos to my Amazon account?  The only thing I received was an offer for a free trial with Walter Presents that I DID NOT set up.  Then they started charging me, apparently, when I didn't cancel it!!!!  I didn't even know I had a free trial. I only searched for the email AFTER I saw the charges!!! It was in my junk mail which is probably where I directed it.