Customer Support Agent Scammed

Another worst experience with Xfinity Support again. When I was purchasing the new iPhone through Voice Agent, the Agent promised me that I would receive BOGO free line when I purchased a new line with the new iPhone. The Agent told me that the BOGO deal would be applied automatically once I received the new phone and activated the line. However, it never happened. When I contacted another Voice Agent, he told me it would not be applied, since I do not qualify for the deal, even though the first agent promised me multiple times throughout the call that I would receive it automatically. Basically, the first Agent just lied to me just to get my business, then when I contacted the Higher-up Support Manager he told me they were not going to honor what the first agent promised me and that I can send the phone back and never use Xfinity again. Is this the way you guys treat your 6+ years customer? This is not acceptable and not the way you should treat your customers!