Customers and suppliers of Monster Slide events claim they are still waiting for refunds and payment, four months since it began a nationwide tour.

A giant slip n slide event which drew 3000 people to Sumner yesterday descended into chaos as unhappy customers spent up to two and a half hours queuing to get a turn.

Concerns about safety were also raised and a 54-year-old man was taken to Christchurch Hospital by the Westpac rescue helicopter with suspected spinal injuries after being knocked over by another slider at the bottom of the 250-metre slide.

The Christchurch Monster Slide event was the first of a series being held around New Zealand, with another one scheduled for Nelson today.

Ticket prices varied from $15 for three slides up to $99 for 10 slides and special lane access.

Organiser Jamie Templeton, from event company Trill Productions, admitted too many tickets had been sold.

By mid-afternoon about 100 people had asked for a refund, he said.

Faith Hensley-Smith bought two $50 "all you can slide" tickets for her children for Christmas but was far from impressed.

She said they had spent hours in the queue since arriving at 11am but by 3pm had only been down the slide twice.

Parents were joining the queue for their children, to try to get them more slides, and some children were blatantly queue-jumping, Hensley-Smith said.

Staff told Hensley-Smith to write down her name and email address, but that a refund was not guaranteed.

Dissatisfied customers reported disappointment with the long queues, the length of the slide, safety and the gradient of the slide not being steep enough on the event's Facebook page.

Templeton said refunds would be managed by the ticketing company on a case by case basis.

"We can't give people refunds on the spot because we run through a ticketing agent. We have a process, they sign a form and we pass that on to the ticketing company and they get in touch and offer a refund. That's the process."

Half of the Christchurch event's 40 volunteer slide marshalls had not turned up which Templeton said had put a lot of pressure on the existing staff.

He was considering employing marshall volunteers for future events.

The $40,000 ramp, built especially for the flat Sumner location, had not delivered the results he wanted and another location would be sought for next year's event.

"We built a massive nine metre high ramp, and installed that for the customers so they could have something really cool to slide on - and to be honest a lot of people are having fun - but it's not giving the distance that we need."

Trial runs for the event had taken place on hillsides, he said.