I was told the phone was free until I saw my bill

I purchased mobile service with Xfinity 1 month ago. I told the sales rep that I wanted to purchase the Galaxy phone. He told me that the moto g phone was free and to take it despite my interest in the Galaxy. After receiving both cell phones, the Samsung malfunctions a month later and I gave to take it to an Xfinity rep who asks me why I'm paying for two phones and one was never activated. The sales rep lied to me to take a phone that was not free and that I didn't need and now they won't take the phone back. This is fraudulent.