Rooms in managed isolation have been sitting empty because some desperate returnees have been able to book more allocation vouchers than they need.
The government is not putting a limit on the number of spaces people can lock in, despite other New Zealanders saying they feel stranded and helpless overseas.
It is mandatory to reserve a room before flying to the country, and the only people who can get rooms sooner than late February must either meet strict emergency allocation criteria, or snap up the very occasional cancelled booking by refreshing the website.
Immigration lawyer Richard Small said the system had become overrun with "desperate people, behaving in a desperate way and just booking everything they can see that pops up".
"It's a lottery. It becomes an accident of being online or having four or five other people to take rosters with you - that's what we've heard of as well, people that have helpers that are constantly monitoring the website and grabbing everything that tumbles out," he said.
On the allocation website returnees are directed to select their preferred dates for managed isolation, which are held for 48 hours while they book matching flights.
To secure their managed isolation voucher, people enter their flight number.
But Small said people have realised they do not actually need to be booked on that flight, for the voucher to be issued.
They are hanging on to multiple options, and he feared people were not cancelling unused dates.
It is something Waikato travel agent Larissa Dunn had also encountered, including people who wanted a second date as back-up in case they missed their flight.
"To me, that's just another waste of a room. I had a lady ring a few weeks ago and she was holding seven different spots in January," she said.
The Ministry of Business, Innovation and Employment (MBIE) runs managed isolation and since November it said about "five to eight rooms" have gone unused each day due to people who had booked multiple vouchers or had flights but no voucher.
It said another seven or eight rooms had been empty each day because people with vouchers had not boarded their flights.
Dee Edge, a New Zealander who describes herself as "absolutely stranded" and helpless in the UK, said it would be amazing to have one of those spare rooms this month.
She and her husband flew over to salvage and sell their Hertfordshire house there after learning it had been taken over by squatters.
They cannot finalise a sale date until she secures flights back to New Zealand and managed isolation vouchers - with the UK's lockdown preventing her from staying in a hotel.
"It's just impossible to get anything ... the dates just disappear within five to 10 seconds. You're on a hiding to nothing and it's so disheartening. I can't tell you how many, literally, how many thousands of times I've gone to that site and refreshed and refreshed and refreshed all day long," she said.
"It's so frustrating knowing there are places free and we can't get one when we need to. We didn't choose to be going back at this time. It's just the order of the process we took to sell the house."
Travel agent Larissa Dunn is among those also sifting the website for any cancellations, for clients who need to get back to the country in a matter of days not weeks.
She said up to 10 people a day were approaching her in increasingly sad and desperate circumstances, including many who were finding it too stressful to navigate the booking system themselves.
"This last week we've had quite a few come through with family members that have taken their lives back here in New Zealand, so they're desperate to get home to be with the family. That, unfortunately doesn't fall under the new category of getting an emergency allocation," she said.
MBIE said it strongly discourages people from booking multiple vouchers they do not need, and frequently contacts people asking them to delete unwanted vouchers.
It said it had locked some accounts so people could not book any more vouchers, while it is allowing slight overbooking of hotels to allow for no-shows, including by 31 people on 19 December.
It did not say if it would consider an upper limit on the number of vouchers people can book.
Martin Small believed it would not be difficult to do, if returnees had to enter an identifying feature like their passport number with their booking.
"That seems a no brainer. That should have been in the architecture of the system from the very beginning. They had a month to road test this system, during October when it wasn't mandatory. This should have been been ironed out," he said.
He said MBIE would have known the voucher system would prompt panic booking.
"Given the millions we're throwing at the border and the billions at Covid, a little extra work on the IT side to give the public assurance that the voucher system has as much integrity as it can, seems a reasonable step to take."
Motueka travel agent Jeremy Matthews has also been helping people book managed isolation vouchers and said the under-demand system had reached "crisis point" with "quite a few desperate people out there".
He wanted penalties for people who booked vouchers and did not use them.
"If there was a $100 penalty people would be incentivised to cancel stuff they're not going to use, that's clogging up the system and making it really hard," he said.
Dee Edge said she also wanted fines introduced, or a requirement for people to confirm their managed isolation booking 48 hours before their flight.
The government has previously said it will not be expanding its managed isolation system to cater for more people, because "the constraint is not hotels, but the essential workforce who care for returnees".