Chinese Commission in Wan Chai. They are the only people who issue visas - all the travel agencies just add a margin on top, with NO greater certainty of getting the visa you want and minimal savings in time or effort. Just go and DIY. It's not hard.
Address
7th Floor, Lower Block, China Resources Building,
No.26, Harbor Road, Wanchai, Hong Kong SAR
Office Hours
Monday to Friday (except Hong Kong public holidays,)
9:00-12:00 14:00-17:00
Download the form from the website, make sure you have your passport, ID card and a photo with you. Get the form from the link below.
http://www.fmcoprc.gov.hk/eng/zgqz/VAF/