Using a promotional code is easy. Open the Hailo app and go to the accounts section (this can be found by tapping the Account Icon at the top left of the screen). From there tap Wallet and then Hailo Credits and then tap Enter Promo Code. Then just enter your code and tap ‘Done’ - you’ll then see your credits added to your account.
You will also have the option to choose which trips you'd like to use your credit on. Before confirming your taxi, you'll have the ability to turn off the credit by moving the credit slider off. You can then use your credit on a later journey. Just make sure it's used within the expiry date!