Fewer than half of Auckland's 180,000 SuperGold cardholders have secured their right to free travel on public transport before new rules come into effect on Friday.
The over-65s have to get one of the city's AT HOP electronic travel cards and have their entitlement loaded onto it to travel for free.
After four weeks of a sign-up campaign, only 25,000 of the 135,000 cardholders needing to change had done so, with a further 13,000 making the first step.
Before the campaign started 44,149 SuperGolders were already using AT HOP cards.
The introduction of the new regime has been problematic, with the Ministry of Social Development, which runs the SuperGold card scheme, initially declining to mail out information.
It had a change of heart following political pressure, but Auckland Transport has yet to get a letter in the post to those on the database.
Auckland Transport has also had to drop an initial requirement for SuperGold cardholders to provide photo ID when buying their new electronic cards, accepting that many didn't have driver's licences.
The agency also says expiry dates for the new concessions which have appeared on confirmation emails, are a mistake, and the free travel concession is open-ended.
Auckland Transport has a more optimistic view of the success of the sign-up campaign. It believes only 90,000 of Auckland SuperGold cardholders use public transport, and it has therefore reached most of those who will benefit.
But the 90,000 figure is a guess, with Auckland Transport unable to tell RNZ News how the figure was arrived at, given the existing regime does not, in most cases, record who is travelling.