http://www.nwa.com/travel/nwati/#asianticket

Scroll down a bit to Taiwan. It's still listed, so I would assume it still exists. It doesn't list a phone number. If you can't find it or it is closed, you can call the international elite line and they may be able to help you. Their number is: 1-218-254-7725. The local NWA reservations line for Taipei is (02) 2772-2188, although it may not be in English.