Apple India — my iphone 7 wasn't powering on

Address: Bangalore, Karnataka, 560076

I had given my phone for service on 18th feb sunday. They said it would take 48 hours to diagnose the issue. Today post 48 hours, they tell me that the issue is with my battery and display which even a school kid could tell since it was not powering on and they have shipped my phone to the repair center for more diagnosis and that this process will take 3 more days!
This is ridiculous for the money we pay to buy the phone.