New Customer - Moved two days back to ATT from XFINITY - Offered $400 by Sales and no trace of that

Package Name : U-verse TV U-family All Included + Internet 100*

Joined AT&T two days back and the lady from the sales team told me that she is going to offer me $400 gift card. However while talking to customer care executive i got to know there is only mention of $200 gift card.

While talking to lady on phone i told him that i am getting out of the contract with xfinity and joining AT&T for internet only but she tole me that with $400 card it will come to be the same.

I really need help on this topic or i might have to go and close my account with AT&T. What should i do and whom should i reach out to understand how to ensure that i get what i was promised?