Housing New Zealand has only managed to answer just over half the calls to its new call centre and there are reports some people have waited almost 40 minutes to speak to a staff member.
The Corporation opened a new call centre in Manukau in February to enable it to deal over the phone with more of the tenants in its 69,000 state houses.
An existing call centre in Porirua was extended and tenancy managers provided with smart phones so they could operate from their cars instead of neighbourhood offices.
The change led to the redundancy of 70 full-time positions.
But the transition has been far from smooth with Housing Minister Phil Heatley previously acknowledging it had "not been without its challenges".
Labour's housing spokeswoman Annette King said Heatley had bragged the Corporation was answering more than 20,000 calls a week, 80,000 a month, over a million a year.
In answers to King's written questions, the minister said the call centre received just under 120,000 calls last month.
Of those, 67,000 were answered, meaning 53,000, or about 44 per cent, went unanswered.
"The call centre has failed to handle the demand," King said.
The minister also said on average calls were being answered within 8 minutes and 44 seconds.
However, that was disputed by King.
"To be frank I don't believe Housing New Zealand are answering calls within 8 minutes and 44 seconds. I don't know where they are getting their averages. Perhaps they're using a cuckoo clock to time the calls.'
"I have heard that people have now been kept waiting on hold for up to 38 minutes. Previously holding time was around 25 minutes. This is unacceptable."
King said Heatley had told Parliament the service was getting better "week by week".
"Yet what each week reveals is more pressure on a few, stretched staff and thousands of distressed tenants."
Heatley said the Corporation had received a "radically" higher than expected number of calls to its 0800 number.
"That is why it has brought forward plans to increase the number of staff at its customer services centre.
The Public Service Association said the call centre had been swamped by tenants who could no longer get face-to-face service from their local office.
National secretary Richard Wagstaff said it was a " classic case" of cuts to frontline staff leading to poorer services.
"We now have this illogical situation where experienced staff in the regions are losing their jobs but Housing New Zealand is recruiting call centre staff to replace them."
Housing New Zealand had a duty of care to its as a social landlord which was being undermined by the call centre, he said.
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