Samsung not honoring prizes for competitions

I got an email from Samsung congratulating me that I have won a Samsung Z Flip phone and that I should send the address for it to be delivered. I rep**** to their email and the next day I got another email from Samsung that they sent me the email by mistake. I promised my phone to my niece as I thought I'm getting a new phone. Now I have to break her lil heart by taking the phone back from her. Thank you Samsung for not honoring your prizes.