Tata Nano — new car battery dead within 15 months

I have bought tata nanotechnology twist full option vehicle from kerala, kannur, nadal showroom. And i have lodged complaint that my car battery has down within 15 months. After several call i got call from service manager from nadal showroom kannur and he told me to bring the car showroom we will replace the battery free of charge. Somehow i taken car to showroom and i met service manager. I wonder such a stupid service manager continuing in the one of the prestigious kvr group, it is a shamefull for kannur. He simply say we cannot do anything you go exude battery showroom in thana kannur, i will instruct them to give irs 3100. Where as i go same battery 2800. Irs because of irresponsible and wrong commitment of service manager my valuable time and huge many i lost.