$400 Device Credit Not Applied – Xfinity Mobile Promotion (December 2025

I went to the xfinity store for nee Iphone 17 pro max. The employee promised to me that I will get 400$ discount and I only have to pay 21$ monthly for contract 3 years. However, I have to pay 31$ for a device. That is unreasonable, I called to xfinity support and they said I was not eligible. That is really scammed and I feel uncomfortable.