The agency we used for our visa application in Hong Kong was called
'Forever Bright Trading Limited.'
We sent our information via email onto 'Alex' at FBT, she checked to make sure we had everything we needed before we made the trip down to HKG. She was extremely helpful and gave us plenty of information on how to find them and worth the extra for them to sort out our Z visa on our behalf. We paid $860 each for our Z visa, well worth the extra so we didn't have to queue up from 7 am outside the embassy.
If you would like to get intouch with them follow this link.
http://www.fbt-chinavisa.com.hk/