The government's got a shake-up of the ambulance sector in its sights as staffing and funding issues continue to plague St John.

The charity runs the majority of New Zealand's ambulance service, but has been struggling with response times amid massive demand for its services.

That's left some whānau concerned their loved ones could be at risk - including an Auckland woman who recently waited for an hour as she suffered a heart attack.

The woman's son Sam, who does not want to be identified, said when his mother began having chest pain one evening earlier this year, they waited to see how it would play out before deciding to call an ambulance.

The pair live on the North Shore - about a seven-minute drive from the hospital there - but with his mother 95 years old, and in a deteriorating condition, Sam wasn't able to take her to the hospital himself.

As her condition worsened, they called 111 at 10.07pm - with call staff advising she should take an aspirin while they waited for the next available ambulance.

But half an hour later no one had arrived, so Sam called back - only to be told that they had yet to even be assigned an ambulance.

"The woman I got the second time, she said 'look your mother's case was logged as a priority one... we're terribly sorry, Auckland has just been flooded with priority one calls'," he said.

An ambulance eventually arrived an hour after that first call was made.

"We're not in the country, we're not on the outskirts of Auckland city, and that was really quite alarming," Sam said.

In a statement, St John Auckland Area operations manager Andy Everiss said Sam's mother's condition was categorised as 'potentially life threatening' when the call came in, but they were experiencing very high demand and all other ambulances were committed to other emergencies

He said the patient was advised to take aspirin while awaiting the next available ambulance, which arrived at 11.07pm and transferred her to hospital in a serious condition.

He apologised for 'not meeting the caller's expectations' and said St John was experiencing extremely high demand for services across the country.

19 incidents under investigation

Last month St John confirmed they were investigating at least 19 incidents so far this year in which staff had been concerned that slow response times may have compromised patient safety.

Twelve in Auckland or the upper North Island, five in the lower North Island and two in the South Island - but Sam's mother's case isn't included in that 19.

Sam stressed the paramedics who helped his mother, and the call centre staff he dealt with, were all incredible and capable people.

But he worries they are working in a broken system - one that isn't coping now, and could struggle significantly as Omicron cases rise.

Sam said the ordeal with his mother highlights issues with the way things are run - he thinks the ambulance service should be run like a state owned enterprise, and that staff who want to work as paramedics are able to travel to New Zealand.

Those are concerns Health Minister Andrew Little is aware of, with the government's ambulance contracts currently being renegotiated.

He told Checkpoint ambulance funding was topped up in the middle of the last contract because they were struggling - but some of the issues continued.

"The Ministry continues to work with the ambulance providers to make sure they're getting on top of them," he said.

Little said the issue of bringing the ambulance service into public ownership was one that would need to be looked at in the next few years.

"As the proportion of the government funding of those services gets up from 90 percent, up towards the 100 percent, obviously the question arises - is this something that we should continue to contract out? Or is this something we should make part of the integral health services that we've got?

"I imagine that is something that we'll have to address in the next three to four years," he said.

But with widespread St John vacancies across the country and Covid-19 presenting increasing challenges, First Union ambulance coordinator Faye McCann said the time for a shake-up in the service was now.

With St John spending high on the list of many staff concerns.

"There's been questions from staff for quite some time about how St John manages its funding and how they manage the service, and I think that the government certainly needs to be looking at this quite promptly," McCann said.