What agencies specifically deal with international trade with Taiwan.
I found a contact for the chamber of commerce at
http://www.tcoc.org.tw/ and daniel@danielliao.com but I was unable to
get an email reply and a phone number led to a wrong number. I am
trying to collect on money owed by a vendor and looking for agency
assistance.

Hi! Thanks for the question.

The government agency which specifically deals with interational trade
in Taiwan is the Board of Foreign Trade, Ministry of Economic Affairs.
You might get better results or actions if you direct your complaints
to them.

The Board of Foreign Trade, MOEA 
1 Hu Kou Street,Taipei,Taiwan, Republic of China 
TELĄG 886-2-23510271  
FAXĄG 886-2-23517080, 23513603 
EMAILĄG boft@trade.gov.tw 
Website: http://www.trade.gov.tw/eng2002/index.asp

Our next link would be more important for you since it provides a list
of contact information for the various Overseas Offices of the Taiwan
Board of Trade.

Overseas offices (HTML Version)
http://www.trade.gov.tw/eng2002/type_sub_list.asp?sub_code=1025&Rnd=4.535276E-02

Overseas Offices (For easy printing but you must have Microsoft Word
installed on your PC to view this document)
http://www.trade.gov.tw/english/overseas/ezprint.doc
 
Here are the specific tasks of this agency.
http://www.trade.gov.tw/eng2002/content_show.asp?NO=1006&html_code=N&Rnd=0.8388483

You can also take a look at other organizations and associations which
deal with matters of foreign trade in Taiwan.

Taiwan Trade Organizations
http://www.washingtonstate.org.tw/English/taiwan-trade-economy/trade-organizations.htm

Search terms used:          
Taiwan trade regulations
     
I hope these links would help you in your research. Before rating this
answer, please ask for a clarification if you have a question or if
you would need further information.
         
Thanks for visiting us.         
         
Regards,         
Easterangel-ga         
Google Answers Researcher