They messaged me back after my long rant to them and said the following:
"we apologize for any inconvenience caused.
all units are brand new and the package has been opened by our team/supplier to provide the correct australian compatible adapter and any non-australia compatible adapter is removed from the package.
please note that different stock could be from different suppliers (local/overseas) depending on the stock availability. regardless of where the stock come from, all units are fully covered by our warranty. in the case if the unit has any problem within its warranty period, please feel free to contact our technical support department through a support ticket here."
It's weird how it wasn't even mentioned on the item listing that the unit was an overseas model. I know DS retail games are region free, but, to the best of my knowledge DSiWare (Is that the name of it?) is region locked.
I'm not overly impressed with them at the moment, as it should of clearly been stated that it was not an Australian model (which most people would expect it would be coming from an Australian online store.
And another thing... it seems weird how they were "replacing the official charger with an accessory pack" to compensate for the delay, I think they were trying to be sneaky so people wouldn't notice that it's a foreign product.
Thank god I didn't buy a PSP Go too.
I wouldn't accept that if I were you. DSiWare and DSi exclusive games are indeed locked to region. I would personally demand my money back.