What legal action can be taken if security deposit is not refundable?

I am 57 years of age living in an old age home at Kolkata. The monthly fees is Rs. 5,500/- and A Security Deposit is 20,000/- only (which is Refundable by three months Post Dated Cheque at the time leaving the old age home). My question is if the S.D. money of Rs. 20,000/- is not refunded at the time of leaving the home, what shall I do or the competent authority to make a complaint?