It does not matter how they do it, it should not be possible for ANY company or person to access funds on your account,
without your consent.

The weirdest thing is that Amazon is directly associated with shady practices like
this. The actual point that I want to make is that Bitcoin is much better, because companies like this cannot get away with
FREE trial scams/Free shit like this, because they cannot automatically withdraw money from your Bitcoin address.

Wait what? How did they have access to your credit card in the first place? They required your credit card information for you to claim your free eBooks right?
Your Amazon account store your credit card details and they are linked to Amazon, so I figure they get access to your credit
card details via Amazon. I will now have to contact the Bank to stop the payments or to chargeback the funds. If they
continue doing this, I will have to cancel my credit card and then ask them to issue a new card with new account details.
I cannot wait for Bitcoin to go mainstream, so that this autocharging bullshit can be stopped.

I assumed you already have Amazon account when you bought Kindle Fire, but do you already have Audible account prior to it? If not and they asked you to sign up to Audible to get the free audiobooks, did Audible not send you an email when you sign up for it and before they start charging you for the next month? From what I know, they give one free audiobook upon signing up but then they charge you automatically the next, although they will email you first. I agree, though about using bitcoin for cases like this. If we used bitcoin, we would not have experienced autocharging into our accounts that websites and banks regulate.
Yes, I had a Amazon account before I bought the Kindle Fire. I had to login to the Kindle Fire with the Amazon account to
use the Kindle and it was then, when they asked if I wanted 2 FREE audio books. There was no mention made about any
subscription and I only became aware of that a month later, when they billed me with the FREE subscription.