Hyundai — Defective Product

I purchased Hyundai Aura from FPL Hyundai (Vadapalani, Chennai)
TN10 BL 7923 and took delivery of it on 17-Dec-2020.
The Car mileage is very poor both in city and highway.
I took it to the Service centre in Koyambedu and there they did the mileage test. On an open stretch in 5th gear the car returned only 13 KMPL. I filled the tank with 36 litres and the car returned only 11 KMPL in city driving and that too mostly free roads due to the current pandemic. The one touch window lock was also not working when they delivered the car.

Please provide a resolution or take back this defectiv product. It has created a huge hole in my pocket. I have spent over Rs.10000 in Petrol for just 2000 Kms.