St John admits it was wrong to run an advert implying funds raised would go directly to crews who responded to the terror attacks in Christchurch.
The ad has been pulled after hundreds of paramedics complained to their union.
Chief executive, Peter Bradley, told Mike Hosking the idea came from a member of St John's fundraising team after the organisation received hundreds of requests from the public wanting to make donations.
"We changed the banner on our website but clearly we got that wrong, it was insensitive and we took it down within 48 hours."Bradley said it was done with the right intention but missed the mark.
He said it raised red flags for him when he saw it and that's why they took it down.
St John has been campaigning to be fully government funded for a number of years, Bradley said.
"The emergency ambulance service should be fully funded or close to fully funded and having to find $65 million a year just to run the ambulance service cannot continue."
He said they urgently need more funding because the current model isn't sustainable.
"St John over the years has done a fantastic job. We cost the government $35 per head of population for our service, compared to Australia which is over $100."
"So we have been very efficient and very effective but there is a time where that comes to an end and we don't believe that it is sustainable to keep funding us as we are. We need to see this funding increase once and for all."
Earlier, First Union's national ambulance co-ordinator Sarah Stone told Kate Hawkesby police and fire crews don't have to fundraise like St John does.
"It's very difficult to run a service, the way they do run it, when you only get paid 73 per cent of what you need to run the services and this means that inevitably workers' wages are hit."
She said St John didn't mean to cause offence but are "woefully underfunded".
"St Johns' response was that they did it because people were asking how they could donate...after they had seen the fantastic work and first class service the workers provide."
"Workers are struggling and the service is struggling to retain workers."
However, Stone said a number of paramedics felt it was insensitive and that it implied the money would have gone directly to the frontline workers.
"Paramedics in Christchurch, those who attended the scene and who know colleagues, family and friends who were affected by the awful events, but also paramedics around the country feel for their colleagues and Christchurch and felt that, at the least, it was an extremely incentive thing to do."
"I think there was also anger that the advert implied in some way that the money would go to those paramedics in Christchurch and that's not how the funding is structured."
She said the money would go into the service but that there's "no way" it would have been allocated into staff wages.
This incident highlights the issues St John has with underfunding, Stone said.
"What it means at the moment is that the service is actually facing a crisis in New Zealand. It's running under establishment which means that it often can't fill the ambulances it has and put them on the roads. So what we are finding is ambulances will be left at the stations because they don't have the staff to fill them."