Do it through their self care portal.

Why am I getting lied to by TIME? I get an email stating I've been upgraded but in actual fact I'm not.

I call customer support only to wait 30 minutes before I get to speak to someone, and this guy was totally unprepared to handle calls decided to blame my settings to my Asus RT68U of not being able to support 500Mbps.

Then I get another call from another person who I'm guessing is level 2 support, but by now I've decided that I do not need 500Mbps within Malaysia therefore I have downgraded to 100Mbps with a renewed 24 month contract.

This utterly rubbish. First I get lied to, then TIME insults my equipment (I probably took more offense to this than anything else), then I got told if I move to a new residence and if TIME is not available there, I have to pay a penalty for their shortfall.