"I caught a punch myself while trying to keep them apart. I got the gas station to ring the police but the fight just went on and on."
When officers arrived, the group scarpered, with one taking Mr Grey's bike. He made a complaint to police, but the motorist didn't want to get involved.
He said the man had his partner and two kids in the car at the time.
"He'd told them he didn't want his window washed and got a bit mouthy so they came to get him."
Mr Grey said it was an indication the window washing was getting out of hand. He called on the council to make it illegal.
General Manager of Manukau Central Business Association Kerry Burridge said the area has long been a hot spot for trouble, and the group has been lobbying police and council to get the issues sorted.
She said it wasn't just the washing, but the aggression, shoplifting, stealing from cars and stealing of cars that came with it that was a problem.
"There's a whole lot of crime that surrounds the area when they are there. It's a nightmare," she said.
The numbers could get up to 30 washers in one day, and at times some of them were just kids, employed to run things for the washers or take money.
Ms Burridge said a recent crack-down on washers in Otara had seen those workers take up residence at the Cavendish corner instead, leading to further issues.
The crackdown was focused on the issues associated with washing - such as shoplifting - and police were working with partner agencies to try and find youth jobs.
Police said they had attended today's incident but the washers had gone by the time they arrived.
They referred further questions to the council, who were responsible for enforcing the bylaw.
The council passed a bylaw in 2013 banning window washing if it is unsafe, intimidating, causing a nuisance or blocking traffic. However, it is legal if it is safe and not causing a nuisance.
Auckland Council's manager of Bylaws and Compliance Max Wilde said it was concerned about the "violent" incident.
He said the alleged incident showed window washing continued to be an on-going problem in various parts of Auckland.
The council reported it received an average 40 complaints a month regarding window washing, 20 of those being about incidents occurring at the Cavendish Drive intersection.
Since December, the council had prosecuted 32 separate cases for window washing. A couple of cases have involved the same offenders.