I received a code word for $100 off your next TopDeck tour providing it's booked through Flight Centre. Just enter the competition to win a TopDeck tour and you'll receive the email.
Not sure if it's a unique code or not.
"As a special bonus, and to help you get your next trip off to a flying start, Flight Centre together with Topdeck are offering you $100 off~ any Topdeck tour booked through a Flight Centre store. It's a great time to experience the world and join like-minded travellers on an overseas adventure with Topdeck. Simply quote your special promotional code: XXXXXXXXXXX6901"