The company does't want me to return my passport...

We would like to inform you that according to the UAE Labor Law that provided a legal protection for wages as below article states:
Article (56):
 Workers who are hired at an annual or monthly wage are paid at least once a month and all other workers are paid at least once every two weeks.
Therefore, not paying wages on the specified dates by law is considered a legal offense with which a complaint shall be filed at the work and workers department attached to it the bank statement to show that the salary has not been received and then claim it through this authority. In the event that the complaint is proven, you may leave work according below:
 
 Article (121):
 The worker may leave work without warning in one of the following two cases:
A- If the employer violates his obligations before the worker in the articles stipulated in the contract or the law.
B- If the employer or his representative legally assaults the worker.
We would like to inform you that if you are an expat and the employer took your passport, then the employer doesn't have the right to take it. So you can claim for it, and if they refuse then you can file a complaint with the police and provide a copy of that complaint to the Ministry of Labor to prove the violation.
Note that the law allows the governmental departments that belong to the Ministry of Interior to take the passport, otherwise it is legal violation such as the private sector.