Landlord denying to payback the Advance

I have rented a apartment in Chennai. During site visit, the condition of the apartment was very worst. I raised concern over the condition of the flat and requested the owner to white wash, clean the home throughly, fix the issues and hand it over for possession in livable condition. The same was promised to me by the flat owner. The landlord didn't the fix the things. But he informed me that the things were fixed. On the day of shift in, I was shocked to see the state of the home and highlighted the issues via e-mail by taking photographs and asked for permission to hire someone for cleaning the home. There was no chance to cancel the shift in as I had agreed to the previous house owner to vacate the home. Vendor visited home to clean the home. But, couldn't clean the tiles in the bathroom and fix the smell in the kitchen. Same was communicated to the land lord. I was requested by the owner to contact Apartment's maintenance team for it. I worked with the maintenance team to get the issue resolved and shared their responses to the owner via mail. I requested for a representative from owner's end to support here. But, he rejected to fix major things seeking the cost involved as a reason. Also, there was no representative sent from owner's end to fix the things. The apartment was not even in livable condition. The water didn't drain properly in bathrooms and utility area. The kitchen was smelling bad. The owner didn't even provide me the agreement copy. To my goodness, I have transferred all the advance and rent through net banking. He acknowledged the receipt of advance and rent via mail. Since there was no support from the flat owner, I wanted to vacate the flat. I vacated the flat a month ago. So far, he didn't refunded the advance. Now, he says since you didn't stay for minimum rental period, he wouldn't refund the advance and denying to give me rental receipts. I haven't signed any agreement. I am in need of advance and rent receipts for income tax exemption. What are my options? Since, he has acknowledged via mail can I send him a legal notice?