The Victorian State Government is responsible fo the housing crisis in Victoria.
The major cause of the crisis is the Melbourne 2030 plan and its predecessors. The plan has its good points, but one of the key directions is the cause of the problem. The key direction which is causing the problem is the one entitled "a more compact city"1. It specifies that "An urban growth boundary ... will be used as a tool to help achieve a more compact city". This urban growth boundary is the problem. Housing affordability happens at the outskirts of the city, and the creation of an urban growth boundary is the creation of a housing affordability boundary. For more information, see the article on Land Supply and Demand.
There are other problems with the Melbourne 2030 plan, but most of the problems flow out of the urban containment policies.
Melbourne 2030 needs to be reworked or replaced, ensuring that it is replaced with something with a much more liberal land releaseLand release
Land release is a euphemism for the process whereby the government rezones land from a lower density zoning (such as rural) to a higher-density zoning (such as suburban). If the government hadn't restricted the land, it wouldn't need "releasing". You can read more about this in Land Supply and Demand. policy.
As well as voting for people who will fix the problems, you should be able to lobby your State MP, and the State MPs responsible for the various departments: