yup write to your local FEDERAL MP not your state MP (tax is a federal issue). people (and their causes) look like a nuff nuffs when they write to members of the wrong Parliament.
if you decided you wanted to write to you state parliament MP or state treasuer asking them to campaign their federal counterparts on your behalf, then feel free to do so, but make it clear thats what you want, otherwise it will get ignored.
here's a quick template if your writting to state MPs (easily customisable to a template for federal MPs)
________________________________________________________________________________
_________________________________________________________________
Dear xxx (pls get their correct title right - they hate nothing more than people not spending 2 seconds getting their title right eg. Mr xxxxx MP, Hon xxxx MP etc)
I/we are writing to you to ask you to campaign your federal counterparts, especially the Treasurer, The Hon Wayne Swan MP, to support Mr Rob Oakeshott MPs motion in the House of Representatives on 13 February 2012, calling for fairer tax treatment of Australian owned microbreweries through excise relief.
[insert what ever else you want to say, eg like chunks Oakeshott's speech]
Yours Sincerely
xxxx