Transfers through blockchain technology

Hey. I am in a middle of a transfer through blockchain technology. I am trading in a platform TopTradePro and when I ask for a withdrawal a guy from blockchain in Switzerland called me asking for 40% of the total amount which must be transfer to me as a reassurance package. He also said that, this 40% is about the conversion and the transfer and that I will receive that 40% back as well. All I want to ask is, if anyone of you ever heard of such reassurance payment. Is this kind of transactions legal? I find it a bit difficult to believe it because this guy is asking for a 7000 euro as reassurance package. You help would be much appreciated!