Refusing to give an employee his passport and failing to fulfill the obligations

Dear sir/madam,

I came to the UAE in January for an employment contract based on a salary of 6000 AED per month as a research studies manager.

Now I didn't get my job accommodation or transportation or anything they mentioned in the labor contract. Even they keep our passports also.

I asked them, if you don't give me the job, give me my passport so I can go back home. They said if I want the passport, I have to pay for the company. It sounds like blackmailing.

Please give me some advice.

Thank you!