I thought I will share my experience here so that others can benefit from my mistake. I put an advert on leboncoin to sell my Samsung S8! I met this guy who tried to bargain, check the phone and then paid me cash of 600 euros! The currency looked fine. I had a coffee in a shop and no red flag yet! I went to purchase some thing from Auchan and that’s where the alarm flag rang! The machines didn’t accept the cash, I altered the cashiers, the staff were very helpful and called the police! Police was very kind and I went to the station to report the scam. I have provided the telephone number of the person, and since the transaction happened in a McDonald’s, I hope they can trace through CCTV. Please make sure to check the currency properly while doing any transactions! I hope the person gets caught and I get my phone back!