It also happened to me!! One pretty big head hunter ruled me out due to "better candidates" for a job for which I had more than 8 years experience in a type of software development that is hardly done in Hong Kong (cell phone). Plus it was a Mobile TV protocol that I had already worked on. Plus the client was UK based and I have been working in the UK for several years. I wonder who these better candidates where since the cell phone software development is next to non-existent in Hong Kong. So, I totally understand your frustration.
In the end I got my job through an agent based in Australia! And my skills wheren't even that close. So I wouldn't trust some HK headhunters.
I think restructuring your application may help but rather try and find different headhunters or direct contacts. Go abroad if you need to, e.g. see if there are foreign headhunters recruiting for Hong Kong in your industry.