I bought a Mahindra H-UPS before an year. Till now I received one complaint and it was resolved within 2 hours of registering the complaint. The mahindra service is very good. They also come once in 2/3 months and checks the inverter for free. I also recommended this to my brother in Thiruvannamalai. He also bought and he has a good feedback about the product. I am a electrical engineer and I feel happy with the performance and the product of mahindra.
The only disadvantage of this product they are not advertising properly and no proper awareness about this product. But the performance is really nice with very good features. I heard from the officials that this UPS can recharge the battery from min of 3V and they experimented it and showed to us in a display.
So, I suggest tat U can try mahindra H-UPS.