Do I need to go back to the Honda dealer?

My 2012 Honda Jazz/Fit had a noisy manual transmission and was difficult to select the lower gears. Honda replaced under warranty everything inside the gearbox (it took 4 weeks to get the parts from Japan). It is starting to make a sound like a bus again and is hard to select 2nd and 3rd again. This time the dealer said they all make this sort of noise (but wouldn't show me one of their cars making this noise!).
So my question really is, 'How do I make them fix it again?'. It's still under warranty.

Btw: I have always driven manual cars and never had a problem. It's definitely not me.

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