i had signed an agreement with company

i am working in an organization, i had signed an agreement with company for working two years for it in place of they were providing me to fund for international exam of coding, and also they would have to increase my pay in case of passing, if i was going to leave earlier i had to pay some amount to them. but now as i have passed the exam they are not incrreasing my pay neither leaving me. as a matter of fact , they did mention the 2 years period as compulsory but for pay increasing they mention as ‘may be’. they did took my signature before entering the amounts and copy of ID card but they did not provide me the copy of that bond at that time neither after that. i just want to leave this company without any legal trouble, as they are have now started troubling me in job because of that bond. i am working in 4pm-12am and 12am-8pm shifts from past one year, neither getting any night allowance neither any optional day alllowance as iam working for them