If you have a promotional code for Osprey, you can use this via the Osprey app.

Download the Osprey app and fill in your personal details.

When you navigate to your 'profile' you will see a promotions tab. Here you will be prompted to enter a promo code. Please note that you will need to add payment details to your profile before you can start charging, even with a promotional code.

Entering a promotional code will automatically change your price plan ready for the next time you charge.