The pair saved for two years for their "trip of a lifetime", taking in South America, NZ, Australia and South-East Asia over nine months.
"We spent the last couple of months in South America and we expected something like this to happen there, not in broad daylight in New Zealand," she said.
"It's been one of our favourite countries, and I guess we've just been really unlucky."
She said if there was "one thing" they could get back it would be the memory cards and USB stick so they don't lose all their photographs from the trip.
They reported the burglary to police, who dusted for fingerprints and are studying CCTV footage, aided by Tom, a police officer who works at Scotland Yard.
However, Nicola said they have been told the area of the Barrett Street carpark they had parked in was a "blind spot" for CCTV cameras.
But she praised police as well as Te Papa security for the seriousness with which they treated the theft, and appealed to the public for any information that could lead to the recovery of their belongings.
"We searched the grass and bushes around the area, and in the carpark and bins, anywhere we think they would dump [our items]," the PR girl said. "There's nothing of interest other than the iPod and USB stick, nothing of real [monetary] value, so we were hoping they would dump it locally that we could find it, but we didn't have any luck."
She said they were "desperate" to retrieve their things and hoped speaking to the media would help.
"We're just hoping that a member of the public finds something and hands it in," she said.
In an added blow to their luck, Nicola said they thought their travel insurance would not cover them, nor would the rental company they hired the van from.
Anyone with information was asked to contact Wellington police.
