You cannot be asked to do work other than what you have been employed to do. The terms of your employment are determined by the relevant EBA, award and your training contract.
In most states and territories apprenticeships are regulated by legislation. This generally requires that any variation to the training contract, including a change in the duties performed as specified in the training contract, must be applied for by either the employer, the apprentice or both. The changes must be approved. If there is a change to the nature of an employer’s business and it affects their ability to provide appropriate work for the apprentice and their ongoing traineeship, they must inform the relevant apprenticeship authority. This is true also if the employer becomes aware of anything else that could jeopardise the training contract.