"Free phone promotion"

I have had xfinity services for about a year and a half. In that time I was promised a free phone. No stipulations. After actually receiving the phone I was told I was ineligible for it due to me not having a number to transfer to it. Something that I was not notified about.  I instantly tried to return the phone but received nothing but lies and run around tactics. Almost a year of fighting and still the phone does nothing but continue to cause issues. I am being forced to pay for it putting me in financial hardship. I reached out to multiple agents today and was fed even more lies about being able to return the phone. I was told I would receive return labels by not one but three different representatives on different occasions. I did not receive on. There is no record for this on Xfinity's end of any of the conversations I have had and I am unable to keep paying for someone elses mistake. How do I resolve this