[General] Note 2 n7105 can't surf on 3G or H+

I bought a Note 2 in Singapore and I can't use 3G or higher network. According to Samsung, although my mobile is unlocked they can't do it anything to solve my problem. Does anyone has a clue how to make this thing works. The other thing H+ sometimes is available, but 90% of the time I'm using E.

Cheers
P.S. it's not a carrier problem.

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