I am a bit confused with so many replies. Forum is not allowing me to post fast !!! What I understand is I need to contact the merchant. I bought it from Cloud Mining Website. How do I contact them ? I tried to send 0.02 BTC, whereas 20 BTC has gone from me. I can not afford this loss. Need to get it back at any cost. In PayPal, CreditCard there is an option to revert a transaction. Why dont we have it in Bitcoin ?