"I say 'You've got to be joking, I've just got here'," Hunter said.
He tried to argue, but he said the Amalgamated Car Parking Services operator threatened to tow his car at nearly three times the cost if he didn't pay.
"It was just 'Sorry mate you got done, there's a sign, it's $150'.
"It seems ridiculous for a couple of minutes."
The entrance to the carpark does have a sign warning the parks are for customers only, but Hunter said there needed to be bigger signs and more of them.
The Herald checked the signs, which did include one notice on the front saying cars may be clamped or towed - but it was too small to read from inside a car.
There was a clearer notice on the inside of the hoarding which couldn't be seen while entering the carpark.
In a similar tale, Glen Yare told how a quick trip to pick up takeaways ended up costing him dearly.
After leaving his car for a few minutes, he returned to find his wheel clamped and a man demanding $150 payment or his car would be towed.
"It was unbelievable," he said.
There should be laws against clamping in New Zealand, Yare believed.
Both men said the Amalgamated staffer was not carrying photo ID and would not produce it on request.
Amalgamated owner Craig Burrows said all his staff carried photo ID clipped to their shirt and should wear them while working.
When told his staff member had been seen by the Herald operating without photo ID, Burrows said the company was not required to make staff do so and had introduced the policy voluntarily.
"He [the staff member] does have one and I can't be in two places at once."
The company was considering whether signage needed to be clearer in the carpark and was prepared to add more.
"We are looking at that carpark and we'll asses the situation and if possible make it more obvious if that's what needed.
"But from experience signage doesn't stop signage from people parking where they shouldn't - lazy people who don't want to walk."