I have been in touch with another dealership , who admits the only dearlership who can solve this issue is Waverley Toyota, they are the experts for all toyota transmissions, but the only catch is the threat of paying out of pocket fees if they work on it and deem it to be normal (even thought it is still under the factory warranty.)
I also observed the noise yesterday in another Corolla ( same conditions idle in gear), I am now thinking its a design fault in the tranny for possible a batch of these cars and Toyota will never admit to that, (past experience).