Changing the way we vote for the Senate

may or may not happen. If it gets through it may still be the subject of a High Court challenge.
For those of you in Upover let me explain.
Downunder has both state parliaments and a federal parliament. The Senate is the upper house of the federal parliament. The states have twelve senators each. The territories have two each. There are 76 Senators altogether. They are normally elected on a "half" basis i.e. six at a time in the states and one each in the territories. If there is a "double dissolution" all the places become vacant.
Unlike the House of Representatives - where the candidate with more than 50% of the vote gains the seat - Senators need to get a "quota" - a certain percentage of the votes. When that quota is filled the surplus votes can then pass on to the voter's second choice and so on - until all the vacancies have been filled.
The first problem with this system is that (a) if you want your vote to be counted then you must vote either "above the line" and give your first choice of party the right to decide where to send your preferences or (b) below the line and number every box according to your preferences. Either way your vote will run until all the positions are filled.
The second problem is that the system of preferences/quota have allowed complex behind the scenes arrangements, especially between the minor parties, which have sometimes allowed them to be voted in on a minuscule number of primary votes. In the present Senate there is a Senator from Victoria who obtained 0.05% of the primary vote but went on to win a seat through preference deals. 
It is this sort of scenario which the government wants to try and prevent.
There is a good reason for this. Cross bench Senators can be extremely powerful. Imagine the not impossible scenario of a very close lower house where every vote counted and the government of the day is relying on independents to keep it in government. Then, in the Senate the two major parties having say 36 seats each. There are four "cross-benchers". The government of the day needs the support of three of those cross bench Senators to pass legislation. It makes those Senators very powerful people indeed. They might only have one vote but if they withhold it then the government must "negotiate" if they can.
Do we want to give people with a minuscule primary vote that sort of power? 
The major parties are opposed to "first past the post" and "optional preferential voting" at federal level - although the latter is being tried at state level in the Northern Territory. Combined with a compulsion to attend the ballot box which is effectively seen as a compulsion to vote this encourages the complex preference deals which cause so many problems.
If there is a compulsion to attend the ballot box then there should be an optional preferential voting system. Nobody should be required to vote for more seats than actually have to be filled. If someone wishes to vote for further candidates then so be it but I find the idea that I vote for "A" and my vote ends up being used for "B" whose policies I do not like undemocratic.