OK!,

After 14++ months with the problem, I finally can get a honda service to fix it upcoming friday.

I have been going to Burswood honda (I live in Perth btw), and They really know how to make ppl piss off. I complained the seat first time in jan 2006 service. and the movement just gone during the test drive.
and I complained again during last service in jan 2007.
They said slight movement on the driver seat was normal (I Didnt think the guy know what he is talking about).
And later when I got home, I tried to call them again to book one of their staff to test drive with me.
They REFUSED, and they refer me with honda customer relation number to complain. even on the service receipt, they openly didnt tick the box for test driving the vehicle (which is a must during every service).

Then I went to Honda North, one of their technician just quickly look at the seat, and try to shake/move sideway the seat by hand (didnt need to test drive it) and he found the seat moves excessively (bingo!) then they ordered a new seat base for the car.
I was bit worried because the car warranty finished at the end of march.
but the warranty still there and they cant refuse

Let's hope everything going fine this friday!