TVS — Battery problem and starting problem.

I have purchased TVS N-Torq in April 2019. Since purchase, always there has been starting problem with self start of vehicle. This has been notified while servicing but there was no solution.
After 3rd servicing, due to lockdown the usage of vehicle was less and battery was completely drained. When I gave the vehicle for service to TVS, they mentioned the battery os completely dead and need replacement. A battery can't be dead on 1.5yrs for any 2 wheeler. There is definitely problem with either battery used by TVS or there is design fault which drains battery and consumer has to suffer paying additional.