The Chinese company knew that it had no right to keep your passport. HIghly irregular. I believe there was a very dishonest reason why they needed/wanted to hold onto it for a period of time, and it has nothing to do with safeguarding the passport to prevent loss. I will tell you that you should still report this incident to the Embassy or Consulate that issued this passport, even though the passport was returned to you. Do it as soon as possible. And be very careful with this organization.