What can I do if someone Illegally demand to pay money as Employment bond?

My company ask me to pay 2 lakh rupees as penalty for 2 years employment bond break ( already worked 1.8 years ). In my offer letter, it is clearly mentioned that after 1 year, penalty is calculated as proportionate amount for remaining employment bond period which is almost 4 months. They were forced me to pay 2 lakh rupees otherwise they will not provide my relieving letter and experience letter. Actual proportionate amount is 33k approx.