Whether to avail paid service of job sites/consultants

I have registered myself on several job sites. I and other job seekers also receive several calls to avail paid job seekers service. Payment required being ranging from 1000 to 5000.  Job sites/consultants executives tells over phone  that  there are  unadvertised vacancies in big corporates and your resume has been shortlisted so you have to pay so much sum to get job. 

Whether to pay or not.  share your experience