T-Mobile USA

I had bought a brand new iPhone which was $45 dollars when I switched over. So couple day afterwards I ended up cracking my screen. So I asked could I return it since I had a warranty. They told me yes they would order me a new phone and which they do I waited about 5 days and it came. They told me to come to the store and get it where they successfully hooked everything up. Now about 2 weeks later the person who gave me the phone said she wants it back and if she don't she will have to pay $700 and loose her job. But I feel that doesn't have anything to do with me I paid $45 for my phone and you gave it to me 🤷🏽‍♀️ You can't ask for it back