Erm I did some research on gearbox changing though...
Ellipse quoted 2.8k before gst. There is another company @ Loyang called Jackson Powertrain (you can google it), they quoted me only 2.0k (if you need the contact I think I took the lady's namecard).
Instead of changing the gearbox, I went down to Autobacs@Loyang to change CVT fluid and it seemed to work?

. The gearbox functioning more smoothly.. there will still be abit of jerking but it is much better suddenly.. still monitoring though...
According to the lady I talked to at Jackson powertrain, she said that CVT cannot be "overhauled". They will just take a recon version and put it in. There is no parts to replace because Nissan does not provide the parts? Yea, I took her words with a pinch of salt though.