NZ Post shot itself in the foot in the lead-up to today's announcement it will ditch the FastPost service, the Postal Workers Union says.
Overnight deliveries will be scrapped from the start of next year after the service dropped by 23 percent during the past year.
Postal Workers Union spokesperson John Maynard said NZ Post had not done enough to protect the FastPost service in the last couple of years.
"People stopped using FastPost because they couldn't be sure of it getting there the next day.
"I worked as a postie for 20 years and in the last few years I was getting people telling me it took six days for FastPost to go from Wellington to Napier for example.
"A lot of people tell us they send birthday cards, even FastPost, up to a week early to make sure it'll get there."
He said when NZ Post put the price up for FastPost in July he told the organisation it needed to improve the service otherwise fewer people would use it.
That it is now being scrapped was no surprise to postal workers.
Mr Maynard said before prices were lifted, NZ Post intentionally slowed down an overachieving standard-post to incentivise using FastPost.
"So they slowed the standard mail and then you had to pay a higher amount for FastPost being delivered the next day."
He said the company had failed the taxpayer.
"What private company would say 'we're over servicing' and start cutting down the service.
"The State-Owned Enterprise Act has three main principles that New Zealand Post is required to comply with. One is to operate like any other commercial company. Well I'm not sure they do when they keep talking down their service."
A general manager at NZ Post, Ashley Smout, said the company did try to save the FastPost service.
"Our leaders would help the local team to make sure we have what is called a clear floor every night to improve it. Then we would make sure in our delivery phase there was no drop off in the service.
"We have had problems, we acknowledge that."
Ashley Smout said the service made up 1 percent of all mail sent and it was costing the organisation millions of dollars.
He said while letters were declining parcels were going to increase.
And postal workers that had been handling FastPost would hopefully be re-assigned to the side of the business in demand, Mr Smout said.
"There will be less people required in the mail business, more people required in the parcel business.
"We would hope, we would aim that there would be no job losses as a result."
Mr Smout said about 80 to 90 workers were involved in delivering FastPost.
A new priority mail service for businesses will be available in and between Auckland, Wellington and Christchurch.