Buy used device

Dear apple team I buy used device from local market and they don't give me any receipt or bill cause it's second hand when I was in dubai it's work and after that I moved to india now it's show activation locked what I do now?????

How many time I talk to Apple advisor they do nothing I ask then if this is stolen then tell me I give to owner they not unlocking not tell me real owner what they want to do with Apple device if someone forget I'd and don't bill then his money is waste tell me anyone please ........give me any way to unlock or return it please