What happens if I have specified fake data but the real number?

I'm supposed to ask a buddy what happens after Amazon Prime expires but he has entered his number. So to explain it now: He wanted to pick up the Twitch Prime packages and made himself an Amazon Prime Account with fake data. The only thing that is real, is his mobile number he needed to verify.

Today he wanted to cancel Amazon Prime and so but can't log in to the account even though the password and so true. But since he said that he used a temporary e-mail, I think that's because of it.

Well, now he is afraid what the consequences can be. He can only log in to the Twitch Account. Is it possible to log back into Amazon via Twitch? And what penalties can he expect?

Nothing. Punishment for what? He did not do anything wrong. Everything is great, Amazon has probably locked the account for lack of payment, done.

Thank you, I'll tell him.

Except fraud, he has done nothing.

What's wrong with that?

Data falsification
Conditions Infringement
Possibly even fraud?

Next, Amazon will claim the prime fee from you…

Do you think that rules and conditions are laws for fun?
Do you think that you can just commit so data falsification?
Do you think you can just lie to and betray such an online shop?

But theoretically nothing can be deducted from the card and that will end automatically, right? He had no intention to use the paid service for free but just wanted to use the free trial just to get this package.

If Prime is not terminated in time, then it will continue to run for a fee! It is NOT "automatically canceled"! Is also very clear in the RULES!
If you do not cancel Prime, then Amazon will collect the money from DIR! Followed by reminders, fees, trouble, debt collection, … Until in extreme cases, the bailiff is at your doorstep.
You have entered into a binding contract and are required to fulfill the contract until terminated.
Is quite stupid to try to cheat a corporation like Amazon…

I think the wrong information. I suggested that he call the support so that the Prime test month terminated and the account is blocked.

He has also used a fake credit card number from any side.

Nevertheless, Amazon will do nothing. The lock in the case of failed payment and done.

And I think the account was not locked because he has enabled Twitch Prime.

Are there no reminders or something? Because many say it would be so. I'm sorry if I'm annoying with the questions.

No. Amazon does not charge a prime. The moment the trial expires the payment will fail and the whole thing will be blocked.

Even if, where should the reminders come from?

If you are so worried, then you should a.k.a. Make "your friend" something so easy.