Nexon XZA plus AMT 2019 - mileage giving only 9 km

Recently brought nexon xza plus amt in chennai 2019 model. From starting, am facing so many issues reverse camera showing reversely , for that they took 5 days for rectification. They have updated entire software .When I drive at rain time the reverse camera is not working properly. Rear seats are not locked properly. More than this am now facing mileage issues which is giving only 9 km. Reported to show room and complaint raised to TATA directly but no resolution was taken for that instead they are giving tiffin box as gift. I don’t know why??? I would not suggest AMT in Tata which is giving worst mileage. Services are not taking care properly. You can connect me @ 7********11