all the same story.. never signed up.. have amazon account.. didnt discover it till 9 months in.. tried to get help from audible and they couldn't help without knowing my account.. (which they couldn't find based on my email or billing address) .. the chat ended badly..
but found solution.. reading amazon boards.
So here's the deal.. you may not think you have an audible account.. but if you have an amazon account.. keep reading..
go to http://www.audible.com click login.. it pulls up your amazon account login.. viola! now.. click membership.. cancel.. and go thru the process cancelling.. Then click on the help, and they have your account info already attached to chat.. select regarding my account.. topic refund..and type being charged for membership i didnt sign up for.
I got a very helpful person.. asked me a few quick questions.. one you will need is when did the charges start.. in my case, january 2015.. so 9 months.. they said perfect.. asked me to be patient while they processed refund.. and 10 mins later.. all done.. gave me the total, and said it would be returned to my account within 2-3 days.
So.. I was disturbed at how they started billing.. and how hard it was to research how to fix it all. but once I found the answers.. it was pretty painless. Unless I post otherwise, you can presume I did get the entire refund as they stated.. Best wishes.. hope this helps .