Advice on DH's work record

We are looking for some advice on hiring a DH. After 3 helpers terminated early on us, and having to let go of two more because they could not do half of what they claimed they could, we are questioning both our own management abilities as well as the general market in HK these days.

Has anyone tried asking (and insisting on) for a reference letter or to request to see helper's previous contracts / passport record to verify whether the helper has actually completed previous contract?

 

Our agent laughed at such request (and we simply switched after that) but we are curious of everyone's way to gain more access to key information.

 

Much appreciated.

 

Alex