Compliance and customer care complaint

I reached out to xfinity regarding an extreme increase in my bill where i was extremely upset and wanted to cancel my services. The service member Amanda from the cancelation department informed me that some promotions where i would receive a discount off my services a "free iPhone 15" with me paying only $10 in fees (which was waved) I then put my SSN in on the keypad to which then the girl was having "internet issues" and transferred me to the phone team to assist me further. Once transferred to the phone team, i was informed that this package does not exist and would not be able to be satisfied. however I verified 3 times on the line with the rep to ensure that is was the offer being given to me and she said yes every time. I even brought up how it seemed to good to be true. I then was transferred to a supervisor who told me no matter what they WILL NOT satisfy this issue even though it was promised. she informed me "you were misinformed, there is nothing I can do for you." I would like to get some sort of contact information to file a complaint with the corporate office