Oh if any of you guys had the same problem as mine, that is purchasing a version that is not SEA region (Mine was European version) fret not. If you shoot an email explaining ur case to Blizzard tech support of ur relevant region, they will transfer your account to your prefered region. Mine is now SEA region.

U prob have to give some reason. I told them I stayed in Malaysia and the latency to Europe will be bad. Also most of my friends are here. So they said they can change. They just mention that if u change region, u lose all previous achievements and scores of the old one. Fine by me coz i haven't install the game yet. 
Also depends on their official policy. But I think if u have a strong enough reason they will allow.