In order for me to use it, I was supposed to press the "promo code" button to apply it to my reservation before completing it. The representative said that all sales were final, and therefore she couldn't apply the promo code. Hotwire's booking works differently from how a conventional reservation made through an online agency works. In exchange for a discount, you give up your right to know the name of the property as well as your right to a refund. In other words, Hotwire isn't for the indecisive, and I might add, you were extra brave to try your first reservation on the Hotwire app instead of through its site. In order to redeem the promo code, it had to be entered before purchase, and it was limited to one per customer. For technical reasons, the representative you contacted could have helped you apply the code to a new booking, but she couldn't apply it retroactively.