If you click on withdraw listing and then tick I didn't sell this item, it will ask you why you are withdrawing it and you would explain it was an accidental double up. I've had to do that a few times. Based on my experience you shouldn't be charged a withdrawal fee.
Thanks heaps for that!! It was defaulting to a different pick up address to usual. When I selected the one I normally use, it worked.
It's only coming up with Aramex courier options, not NZ Post courier as well, and when I choose Aramex non signature, it's saying the address doesn't match NZ Post postcode finder, so I can't proceed. Has happened on all 3 auctions I've tried. The addresses are valid on postcode finder website. So frustrating.