$200 gift card for switching to Xfinity mobile

On May 2 I called xfinity at 3pm in the afternoon and spoke with Viant to make a couple of changes to my cable tv account. After those changes were made successfully Viant offered some options for changing my mobile phone service.
He said if I switched from TMobile I would receive $200 towards the cost of breaking my contract with TMobile. He also described the one year of no payments and $40 per month thereafter for Xfinity service.
To break my contract with TMobile I had to pay $618, mostly to cover the remaining cost of my iPhone 16.
I accepted Viant’s offer; the $200 was definitely an inducement to switch.
Yet when I completed the steps to make the mobile phone switch,  the Xfinity mobile agent knew nothing of the $200. He said perhaps it was offered by Xfinity cable and internet. Either way it was an offer made, an inducement, which I relied upon to make the switch from TMObile to Xfinity mobile.
Please tell me the process to receive my $200 gift.

Sandra [Edited: "Personal Information"]