china Travel service or the PRC Commision, information here:

852-34132424 (Live Answering Telephone available in office hours )

Email: fmcovisa_hk@mfa.gov.cn

Taken from:

http://www.fmcoprc.gov.hk/eng/gywm/lxwm/default.htm

The only difference if you give your paperwork to CTS/a agent is you don't have to go and do all the legwork/waiting around in person, but they charge you a little more IIRC.

Cheers and cafe lattes,
IM