Briefly, my father is ill and I have to return to australia before my Non B/Retirement Visa is due for renewal/extension (May 2, 2012). I do not think I will be back before may 2 so I need to know if I can go to immigration now and extend my visa (almost 11 weeks early), I use the bank balance/income method.....so before I head off to the aust embassy in bkk for the stat dec I would appreciate any input. Thanks.

It might help to know what office you will use as it varies - but in general that is very early and they seem to be less inclined to issue early these days. I would just obtain a new non immigrant O visa from an honorary Consulate like Brisbane for your return if not in time and then start retirement extension again from that. Nothing lost by doing this (other than one time visa cost but if you do not buy a re-entry permit it will be mostly off-set and three extra months before the next extension.