Harassed by tenants. Want to safe guard my hard earned house.

I had rented my apartment to 5 bachelors on 1/3/15 on the oral condition that they don't booze/ smoke inside the house. To my nightmare, apart from these 5 who were the only authorised tenants, there were 2 other different men plus a girl who were living every time I visited. I found that these people were consuming alcohol at all times in the day & the house stinks of nicotine even after they've vacated my house. Also the house was kept v.dirtily! I warned them that this kind of behaviour was completely unacceptable everytime I visited them. I also warned them that they will have to pay a penalty for this. After 11 months, I terminated the agreement & got them vacated. They paid me an advance of 1.8L spread over a period of 4 months from the time of getting into agreement. I returned 1.25L at the time of vacating & 1 month later I gave back Rs.15,000. As per the agreement I cut 24,000 for painting & cleaning. They are creating problem by harassing over the phone & email saying that I've to pay them the remaining Rs.17,000, else they will take the legal course. I don't wish to return this amount b'cos of the horrible nightmare I had to experience due to their uncultured existence in my house b'cos of whic my health was a victim. Since the house was maintained badly I've incurred expenses upto Rs.8,500 for replacing kitchen chimney, door lock, cupboards maintenance bathroom fixtures repalced, since they had badly maintained all of these!! The remaining is another 8500, which I don't want to pay back for the mental torture I am living now & lived through while they occupied my house plus they violated the written agreement as well as the oral agreement. Kindly advise me urgently as to how I should proceed & handle them. I want to safeguard my my hard earned property & peace of mind.