Hi Pukunui,
I think you might be able to do better than that if you call Amazon directly.
I am in Wellington and was in the same boat as you. I had already emailed Amazon before I got the second "shipping delayed" notice yesterday, so decided to stop sodding about and rang them. After a very polite discussion (which included how crap our cricket team is at the moment) the guy at the other end gave me a profuse apology and - at my suggestion - canceled the order and made a new order for the 3 core books as seperate items. I was told that I would get a total refund for all shipping costs (saving me $27 or so - I only went with "standard") once the order was processed and the price of the books was discounted so that I was paying the same as if I had ordered the gift set (with a pre-order discount).
The books shipped this morning, and the refund for the shipping costs has already turned up in my bank account.
I will still get the books about two weeks later than I hoped, but I only paid NZ$79 for them so am pretty content.