You have mentioned your designation as ‘Trainee’.
The Trainee/apprentice is appointed as per Standing Orders of the Management/Apprenticeship Act.
Find out you are appointed under which rules?
The service agreement is signed in lieu of what extra ordinary favor by the company::::: e.g. training from some certified Instt. that shall add to your qualification? If no extra ordinary favor was granted by employer the service agreement may be unconscionable.
Did the employer demand original certificates in writing? Has it issued any acknowledgment?
The employer can not have lien on educational certificates of employee.
It shall be appropriate to show the job advt., interview call letter, selection/offer letter, appointment letter, demand and acknowledgment of original certificates, and service agreement etc to an able Labor Law Consultant/Service Lawyer and proceed under the expert advice of the lawyer.
You may go thru other threads at:
https://www.lawyersclubindia.com/experts/Breaking-of-service-bond-500856.asp#.VDp9nWeSwb8
https://www.lawyersclubindia.com/experts/Employeer-harasment-not-releiving--500951.asp#.VDp8lWeSwb8
https://www.lawyersclubindia.com/forum/Pledged-my-educational-certificates-how-to-get-it-back--109483.asp#.VDqAHWeSwb9
https://www.lawyersclubindia.com/forum/Dupilcate-10th-and-12th-mark-sheets--109977.asp#.VDqAGmeSwb9