Original certificates held by employer

Dear sir/madam, I'm working as a teacher in a private school in chennai. I was asked to submit all my original education certificates for employment. Though I don't like to submit I had submitted as I came to know that schools demanding original certificates for employment. They didn't let me know their rules and regulations. But I signed in my appointment order that I adhere to rules and regulations of the school management. Later I joined there they extracting so much work from teachers. Teachers have to involve in non academic clerical works. Also if v come one minute late to school, they cut 1 day salary. One day absent means two days salary cut. But v have to stay in school for 2 hours as coaching classes after school timings get over. I really fed up with issues. Now I want to get back my original certificates. How can I approach legally. Because its waste of time to simply asking them. They mentioned in appointment order that if I quit in the middle I have to pay 3 months salary to get certificates. Why should I pay that as they didn't let me know these rules. If they inform these I would not have join in that school. Pls give me legal solution to get my original certificates for which I worked very hard.