Where you are pulled over for a preliminary breath test and the police believes that there is alcohol in your system above the allowed blood alcohol content (BAC) level, Victoria Police (the police) will usually ask you to do a subsequent evidentiary breath test. This is to verify the results of the first test.
The police can perform an evidentiary breath test on site, in which case they may ask you to remain in place for a maximum of 3 hours, or they may ask you to accompany them to a particular location (police station, medical centre etc) to administer the test: Road Safety Act 1986 (Vic) Section 55.
Failure to comply with the latter is known as Failing to Accompany. This is an offence under the Road Safety Act 1986 (Vic): Section 49(1)(e). This charge will likely be heard in the Magistrates' Court.
There is only one defence to the charge, this is the Defence of Substantial Character under RSA s 55(9). Essentially, this means that there must be a substantial reason, other than the possibility of incriminating yourself, as to why you cannot accompany the police. You can refer to the DPP v Ellison for a discussion about this defence. Here is a summary of the case: Magistrates' Cases.