Colive Golden Square - Regarding unreasonable demand of money

I rented a colive apartment in Chennai during August. Before booking the room I informed the agent that I can't stay for more then one month so I need apartment for a month. At that time the agent said that is fine. I will have to pay one month rent and advance and I will get my advance back once I vacate the apartment after processing. He didn't mention about the separation charges or electricity bill at all at that time. During my check in process I was informed about the separation charges but I was not informed the exact amount. The condition of room was horrible. It was full of mosquitoes, the internet was not working in my room properly and I was not provided key for my room ( I was staying alone in one room) or cub board until I asked for it multiple time. I was assured that they have food option available but It was not provided to me. The mattress and bed sheet were also bad and there was no blanket but the agent told me that they will have blanket in the room. After complaining multiple time none of the issues were resolved and due to covid cases in Chennai I decided to vacate after just * days. I assumed that they will take rent for august and may be I will get some money from my advance. But recently I was sent an invoice in that I was charged separation charges three times and now they are sending me emails saying that I have to pay them money. This is just unacceptable they didn't provide and service but they want more money now.