Bait and switch

I was looking to upgrade to the iPhone duo. The current promotion says upgrade and trade in to save up to $1000 on the iPhone duo. So I plugged in my 16 pro max and sure enough it says “save $1000 when you trade it in”. No where does it state up to $1000 at this point, just that the phone is worth $1000. So I go to check out and the offer drops to $500. Nothing is stating why it dropped. So I open a chat with an agent and even the agent confirmed my phone is worth $1000. They advised me to complete the check out myself but when I go to pay it drops to $500. To me this is a classic bait and switch. This is beyond frustrating and I thought Xfinity was above these tactics. I’d like to continue being a customer and upgrade my phone but this has given me a terrible taste in my mouth.