Holden has withdrawn further from communication with the federal government.
A delegation of car industry workers and union officials will arrive in Canberra for talks with government officials on Tuesday without representatives from the Holden factory floor.
"Unfortunately, Holden indicated that it would not release any representatives to go to Canberra," said John Camillo, South Australian state secretary of the Australian Manufacturing Workers Union.
"They said they didn't want to play any politics and didn't want to release them."
The delegation will be made up of representatives from Toyota, Ford and car parts manufacturers.
"As far as I know they have never done that before. I gave them plenty of notice," Mr Camillo said.
The snub is the second from Holden which last week turned down a government request to meet a visiting executive from its US owner General Motors.
Industry Minister Ian Macfarlane had asked to meet GM's head of operations in the Asia-Pacific region, Europe, Africa and the Middle East, Stefan Jacoby. He said the snub showed "a lack of sensitivity" towards the state of the industry.
It followed General Motors' decision last month to shift its Australian chief Mike Devereux to Shanghai by the end of the year.
Mr Devereux had sealed a deal with the previous Labor government to continue to make cars in Adelaide until 2022 and to continue to maintain a design presence at Port Melbourne. The agreement signed by prime minister Julia Gillard cost the federal government $215 million, the South Australian government $50 million and the Victorian government $10 million.
Mr Camillo said workers wanted information.
"The shop stewards are copping pressure from the workers every day asking what's happening. Every day they are reading something in the paper. They want us to do something and they keep asking us - what is the decision, what's happening?" he said.
The change of the government and the new minister's decision to refer the question of car industry support to the Productivity Commission rather than honour Labor's agreement meant Holden had already missed the deadline for gearing up to retool its production line during the Christmas break.
"If you are going to make new models you need to take advantage of downtime," Mr Camillo said. "They would have worked around the clock for those nine days reconfiguring the production line and then come back at Easter. That opportunity has gone now."
If Holden withdraws from Australia after its present models expire in 2016 Toyota is likely to follow. Ford has already announced its intention to leave in 2016. The withdrawal of all three manufacturers would lead to the withdrawal of the component parts manufacturers. About 200,000 jobs are at risk - one-fifth of the 1 million-odd workers employed in manufacturing.