Try all avenue to reduce the latency just short of paying a $1,000 a month lease line to play online game.
or convince Blizzard to setup a server here, just like Starcraft 2!!! lol

When I was using Starhub and ran into your problem, I called them, the technical guy gave me the impression that they need to work with their business partner in US to 'tweak' the setting, if it was not a faulty system problem or maintenance work issue. Regardless, I believe Singtel/Starhub has to do something about it as long as your dun allow them to close the case.