Do not pay anything to manpower consultancy for a job. The company pays them for recruiting people . Did you have a face to face interview by the company persons so far ?If Not , why not ? You do not have to handover your passport for a visa , only passport copy of front , back pages required to apply for a workvisa with your degree / diploma copy only and Police clearance certificate required -copy again.

For a Trainee , you should be offered a minimum salary of QAR 4000 + accomodation and transportation.

Otherwise no point going for it .
Stay where you are .

Better to be a LION in your homecountry than to be a monkey in an alien nation .