File a complaint, blatant bait and switch repeated failure to honor iphone 17 promo issue

I ordered the phone via the app, upgraded to the premium internet, took screen shots of the purchase every step of the way as I have heard reports of Xfinity using deceptive practices. 

Was supposed to receive credit monthly for 24 months totaling $400. 

Went to the store when I didn't see my discount, they said that I needed to upgrade all lines to premium to get the promotional upgrade, that was never part of my checkout process. 

after repeated calls to customer service, which to be honest is hard to communicate, they assured me that I followed all steps needed to receive the promotion, I ported a number, activated new line and opted for the premium monthly data charge.  

She filed an advanced support ticket, which she said would be resolved with in 7 days, this was January 6th I received a text message every day after the 7 days saying my claim was still being worked on, I finally receive a text on January 21st saying that my request was denied, clicked the link to see why and no information. 

Claim number [Edited: "Personal Information"]

Calling the customer support team takes hours, as they transfer you to one department to another. Its only $16 per month but the principle is there and this is very frustrating. I have 6 mobile lines with Xfinity and have had their internet for over 10 years. 

I'm past my return deadline; I would like an explanation as to why I didn't get the credit or give me the credit. If denied I will file a formal complaint with FCC,