There are 3 members of Parliament who supposedly represent you. Write to your MLA and both your MLCs expressing your support for PR and your concerns about their party's stance. If you are a member of a political party, try to influence your party to be flexible and support the interests of the voters rather than just the party. Talk to your friends and colleagues about how undemocratic the current system is. Tell them how Proportional Representation is the best way to fix the problem.
Personal contacts are the way to build a grassroots movement.
Join the Victorian branch. Make a donation. Even better, become active in the society. Tell your friends about the Society. We are in the phone book, and on the internet.