400 usd discount not applied after buying phone

Hello,

I recently brought an iPhone 17 with the promotional discount. The chat agent helping me out assured me that after the purchase I will get the credit. After getting my phone and moving the number, I did not get the discount. 

I chatted with live agents many times and opened tickets through them but always got declined saying my selected plan was unlimited and I needed the premium unlimited option for the discount. This problem was done by the agent and not me, why do I need to bear the consequence? 

I explained them that I have the screenshots and I was given a confirmation by the agents but still they are denying to add the promotional discount. This was the most recent ticket ECMO017501033. 

I am very unsatisfied how Xfinity is handling this. There agents sold me something with wrong information and Xfinity is not agreeing to solve it, almost feels like a scam. Tell me what I can do or get some kind of compensation through credits?