Sales rep not following through on promotion

A rep named Zachary (edited per guidelines) was at my home this past summer (7/22/19) and you me get my family switched over from verizon and upgraded our phones on a promotion. part of the promotion was an offer of a $250 gift card for each phone turned in. He had processed two of them right away (which we have received), but he came back a few days later after we got the final phone activated on our account. He overlooked issuing the giftcard when he finally got this last phone. Can you let me know what you can do to resolve this.

Thanks, Patrick (edited per guidelines)