Fraud through online booking by claiming goods are cheap

I talked about buying an empty bag of potatoes, he promised to send me to our address at a very good rate, we made a bill of 54000 thousand in which he asked to put 4000 as a booking first, I put 4000 in his mentioned account, after that he said that you will have to pay 50%, then I said that you had said only this, he said sir This will not be possible, after that they stopped talking and our 4000 rupees were killed.