@Melanie467
Hi, my advise is to call Airbnb ASAP and try explain to them what happened.
Sorry, I don't know the airbnb NZ phone number.
Please don't cancell the booking yourself let Airbnb do it for you.
Because they will penalize you for cancelling it youself.
Hope it helps, and as @Gerry-And-Rashid0 said please take your time and read as much as
possible on this great CC to get as much information as you possible can, how to be a great Airbnb host.
I talk from my own personal experience. I have learned so much myself and still learning!
Welcome and happy hosting!