I have tested this website my self, when you request your btc back they explain that they need documents from you to get your own btc back.
https://multiply-bitcoins.eu/ 
How come u invested here ?
It is a very old site which has been scammed many days before..
And afterall it was a ponzi scheme , EVERY ponzi is meant to be scam atlast and you dont need to make a scam accusation for every ponzi scam..
You are a newbie so u dont know much about ponzis i think..
Just go around this forum and learn another better ways to earn bitcoins !!!
