I had exactly the same problem with exactly the same item.
In the end when I went to get my DP fitted I had a CP-e turbo inlet pipe and Cold Air Intake fitted instead because I was tired of waiting. If you want stuff through MPSG and they are having their now legendary corksport stock issues, see if you can swap it for something else (unfortunately it will probably cost more) that they have in stock, otherwise you will be waiting forever, just forget about getting corksport gear through MPSG for the sake of your own sanity.
Your other option, which may or may not work is to order direct form Corksport. Since you are in NZ you just might get away with this as when I tried they saw I was from Australia on my shipping info and they canned my order and told me to order through MPSG. I already had one of order at MPSG and had paid for it.
I'd say just order from Troy (2XS) or try another distributor, but that doesn't help as MPSG already have your money and it should be easier to organise alternatives with them but that is not easy with their bad communication skills. Otherwise you can see if they can just refund you and get your gear from elsewhere.
I feel your frustration, but I managed to work something out eventually.