OLx scam

I sold a book on OLX and I got a message from a person that he wants that book, so I said ok bhaiya and then he said that he will make the payment online and then I said ok then he said that I will send you the QR, you press pay and the payment will be refunded and it did not happen then he said that madam the payment has not been made, you will have to do it again, otherwise I will file a police case.. I pressed the pay option one more time and instead of the payment declining it was successful.. And now his phone is switched off