no company/person is supposed to keep hold of your passport - unless it is for security reasons. If you think keeping the passport safe at your home is a problem, usually companies offer a fire-proof cabinet in which the passport is kept safely for its employees.

It is illegal to keep witholding passports. it has been a bad practise in the middle east for many years, but now im sure it is not allowed and a complaint will be considered valid.

A passport is only governments property, only a court has the right to hold passports.