Extended working hours, only1 day week off,delay in pay hike,etc.

I don't know if this is stupid or irrelevant. But i need help. I am a graduate in B.Arch and have 1 year experience of full time job in architectural firm in bangalore. after that i joined this private real estate office in bangalore. I rs.20000/ month salary in my previous work place. When i attended interview , in the current office, i asked for hike of rs.10000/month for which i was refused at that point of time,but was promised after 3 months of my work and they would pay 25000/ month as of now. The only correct information i was given was that there is no week off on weekends ,but on Tuesdays. also i was told that i could take leave whenever necessary. work time was also fixed from 9:30 am to 6:30 pm. I worked extra hard for 3 months in order to prove myself eligible for the promised hike by extending my work for 3-4 hours or so. But after 3 months, there was no hike and it postponed for 3 more months. Even after 3 months I did not show any sort of disinterest in work hoping for hike soon. But the work hour extended for half an hour more , not even 1 day of paid leave was provided for sickness also, salary was deducted in-spite of me promising to provide medical certificate. also restriction was made for taking leave during emergency and salary was deducted. No written document was provided after interview for joining letter, salary slip, etc.The only proof that i have is the bank statement of salary transfer to my bank account from the company. My questions are:- 1) Do private offices have flexibility to change rules like this random manner? 2) Without offer letter, can a private office like this run with employees? 3) With all these complications can i fight for my pay hike? 4) Can a private company be sued for all these things? Please help me with these issues as my cost of living is too high in the locality in Bangalore. i shifted to this place of bangalore from my sister's place just which is far away to commute only to work efficiently. Also the MD is watching the employees keenly on the cc camera which makes us feel conscious, he also passes personal but mild comments. Always expects more work when we ask for hike but doesn't do that. Right now im not in position to change my job also due to financial commitments. I dont know anything about employee right and dint find anything useful online.