FIRST Union says The Warehouse has implemented its worst restructure in decades.
The retail giant announced on Monday that between 120 and 140 full-time jobs would be lost as a result of adjustments to the company's leadership structure.
Efforts will be made to move as many affected employees as possible into vacant roles, and they have been offered free counselling.
Kate Davis, FIRST Union organiser, says The Warehouse has sent mixed messages to its workforce and caused "mass confusion".
"There was not enough time during the consultation process, and now interviews have apparently begun today when the jobs aren't even up on their website yet," she says.
"It's a mess, and [union] members need answers."
She says due to "misinformation", some workers have been led to believe they will be made redundant if they don't apply for any of the new roles - the limited hours for which don't suit many employees.
Some are worried that if they no longer have a 20-hour contract, it will affect their eligibility for the Working for Families benefit.
"They do not have the basic right of job security - they are living in limbo, and all this while underemployment figures remain very high. People want more hours and women are hugely overrepresented in these figures, yet companies like The Warehouse are making these moves."
Ms Davis says the move to "casualise the workforce" uses the law against workers, as it makes them partially redundant with no redundancy package.
"The problem is the company is forcing workers to apply for a job with a cut in hours, and will then say there is no partial redundancy because the worker applied for the new job," she says.
"[The Warehouse] is using the worse (sic) possible form of restructuring by throwing everything up in the air and making far more people apply for jobs than they need to, creating far more stress and concern amongst workers and members than they need to.
"How many more million dollar executives are they going to hire while workers sit desperate for more hours?"