I would like to share my experience. Admin please advise if this needs to be posted in any other section or please pin this for the information of new users.
I am an experienced trader since many years. Being a part of many telegram groups of tokens/exchanges is common for us.
I was contacted by a random user on Telegram claiming his BTC is frozen and withdrawal is not allowed in his country (Algeria) and he needs my help to recover it for him. He offered me 10% commission for this task.
I knew it was a fraud instantly but I wanted to understand what exactly they do, so that I could educate others. I played along.

He told me of this exchange :
ECHOTIXBETI made an account and logged into this exchange, it looks very much authentic, a perfect copy of some good running exchange.
After that he asked for my user ID for an user-user internal transfer and instantly my account reflected BTC worth $14580
I knew that this was just a fake number and there is no point trying, I still tried to withdraw it to see what would happen and was greeted by a standard fraud notice that your account is locked and to withdraw this sum you need to deposit some X amount of Crypto
I told him about this on Telegram and he replied, oh! even you cant withdraw it! Damn!.
Just send the BTC back to me I will see some other user to do this.
By then I had clearly understood their business model and I no longer needed this scammer to bore me more. I blocked him on Telegram, he instantly messaged me from another ID swearing at me and calling me a cheater who robbed his BTC

I blocked him again and after that there was no sight of him. This was my experience which I wanted to share with the crypto tribe, as all users may not be aware and get caught in such tangles.
It makes me remember of another fraud exchange some 5-6 years ago (was even listed on CMC) "Fedelio" or something similar.
This exchange used to have prices more than market rates and that's how I got hooked to it seeing XMR prices almost 10% more. I saw a quick arbitrage opportunity and jumped on only to loose my investment. they took deposits and never let anyone withdraw, they kept asking more funds or their fake agents would contact you to help you resolve it by contacting hackers etc. etc.
Bitter lesson learnt.
Hope more users who have faced something similar share their experience on this.
Thanks
PS: Not your keys, not your coins. Always store crypto on self custody wallets.