yeah, having the tranny in 2 won't let it shift to third. it still goes through first and second. they have the options there for snow/ice and going up/down steep roads.

it sounds like the tranny's had some wear. how many kilometere does it have on it? maybe the previous owner beat on it a bit (ie, neutral drops)

if you haven't done so recently, try changing the tranny fluid. beyond that, transmission rebuilds for autos can be fairly pricey.

and no, you can't replace a clutch on an automatic.