Discount appears to work on Gift Vouchers as well as bookings. no expiration date indicated in promo email received.
A few options I found Chch -> Kaikoura one way is $59 so comes down to $47.20 Blenheim -> Kaikoura one way is $59 so comes down to $47.20 Chch -> Blenheim one way is $79 so comes down to …