Xfinity Complaint Fraud

I moved from T-mobile to XFINITY Mobile due to great trade in offers they had quoted me. Once I agreed to transfer my services everything went well until I called the next day to start my upgrades as promised by the agents, it turns out they cannot offer me the promotion for trade, instead I was told I can only upgrade which is not as good as the original offer, the issue was the agent should've processed my trade ins as new lines and not existing lines to take advantage of the promotion. Now I'm paying the price for an agents mistake and Xfinity will not take any accountability, the original offer cannot be honored, they told me I have to leave Xfinity and reactivate again as new lines to take advantage of the promotion, which is unacceptable and poor business.