When I was living in HK, I used to hire the guys via local agencies, usually with great successes, but there were issues in some cases, like the wrong guy turning up at my apartment.
After a while I found it much cheaper to hire directly the guys listed here: gayHK.com
As long as you can text them in English, they will use google translate to figure out what you want and will turn up at your place and usually deliver. If they don't, well it isn't that expensive, so you haven't lost that much. Then you can build a relationship with those that always perform and keep them as regular.