$500 gift card scam

When I signed up for xfinity late 2022 or early 2023, I was promised a $500 visa gift card for signing up and a $100 visa gift card for each phone we switched over. I got in contact with the mobile department and they took care of the $100 gift card. But when I called back to take care of the $500 gift card they said that it doesn’t come up in their system, and that the only promotion they had was for switching your phones over. There were plenty of advertisements on their website about this and many other people signed up for this same exact promotion and are having the same problem with not receiving their $500 gift card. Fix this now! Where is my $500 gift card I was promised and that was agreed upon?