Tata Motors — Tata Nexon Complaint

I bought a Tata Nexon (Automatic) in August 2021.
The last 10 months, driving this car has been nothing short of a Nightmare, and If I could afford it, I would probably donate the car back to Tata Motors.
There have been multiple issues in the car since Day 1.
1. Mileage: The car's promised mileage is 16-17kmpl in a city drive. However what I am getting is around 8-9 kmpl. With the rising fuel prices, this has been absolutely draining.
Though there was a complaint raised earlier about it with the company, the solution was Absolutely bizarre and the results were unsatisfactory. The technician filled the entire tank during an on-road trail, drove around for 12-15 kms in empty roads, refilled the tank to prove an average on the basis of that.
As a layman, I don't understand how on earth is that a fair judgement of the performance of the Mileage? I want to understand if this is the company policy, or the technician took me for a 'Ride'? If it is company Policy, then I am sorry to say that the company is just cheating on their customers.
2. AC: This has to be the strangest complaint I have ever made for a car. The AC stops working, when the car is not moving (stuck in traffic etc), and would start cooling once the car is in motion. So which means, during Delhi summers (temp around 43-44), when stuck in traffic, one has to bear the scorching heat, and only be relieved when the car is moving. However this is something that happens erratically, and is not a consistent problem. This was also reported, and on the day of inspection, it showed no issue, and thus the issue was crossed out by the technician.
3. Other Miscellaneous problem: There are many other fringe problems, like the screen flickering, the automatic roof not working, 1 side of the front light not working, Indicator light doesn't stop blinking. But again these are problems that don't always show up, and while I am not getting a solution for bigger problems, these are the ones I would rather not mention.
4. Battery: Now this is the first time I have to write this complaint for a barely 10 month old car. I recently took a trip to Corbett from Delhi (around 250kms). Approximately 100 odd kms later, we stopped the car for refreshments, and the car didn't start. Now we are on a highway, with a car that's not working. We were lucky to find a mechanic and somehow get the car jump-started and managed to come back home. This was on Thursday. On Sunday, the car didn't start again. And now the car is in the service center, with no information about what the status of the car or battery is.
5. Customer care service: Let me state, without any exaggeration, that Tata Motors (both Sab and Treo), have the absolute WORST customer care executives, who are clueless, incompetent and impolite. I would like to point out the incidents that have happened.
i. Somewhere in January, the car had gone for its second service to a Sab motor service station. Around 2-3 February, 2022, the car had another breakdown, where the coolant had leaked and the car engine heated up. I called their On Road Assistance, who took the car. The car was then sent to a Treo service station by the On Road Assistance Team. Treo informed me that it'd take around a week to fix the car, and there seems to be damage and thus, insurance has to be used. I also got a call from Sab motors for a feedback of the service, and when I mentioned the current situation, they were blaming me for sending the car to Treo (even though that was not sent by me). Now I had a family function and I was out of town, while the car was in the Treo Service Center. I came back around 18th Feb, and called the service center for an update, and was told it'd take some more time. I received the car finally somewhere around 27-28th February 2022. A 25-26 day period to fix coolant damage- with insurance money used and additional payment of 5-6k from the pocket.
ii. Since around 15th May, I have been getting a call from Sab motors that the car's third service is due. Now I told them that neither the time nor the kms were complete, but they insisted that it does not matter, and that I should send it. I scheduled a car pickup somewhere around the first week of June, but before that only the battery breakdown issue took place. Now the car was picked on 6/6/22, after which I got a call from the service advisor about the car. I told him the multiple complaints, majorly the battery issue and also mentioned the due service. He told me that the service isn't due right now because the kms and time is not complete, so he'll just look into the battery issue. I was fine with it, though this was also something that was mentioned earlier by me. Today is 8/6/22, and I have not been informed about the status of my car or what is happening to it (though I was told I would receive the car by tuesday 7/6/22). After multiple calls to the advisor and the center, I have only just been informed that the battery is being recharged, and would be given back tentatively by tomorrow (9/6/22). What I fail to understand is how a 10month old car's battery discharges (when the car has run an approximate 11000 kms in 10 months). Also when I mentioned that ideally the battery should be replaced as it is under warranty, the advisor told me something about protocol and also hinted how it could have been discharged due to my fault.
All in all, I am having a painfully terrible experience with the car and the service center. I am not expecting any resolution from this company anymore (because of how they've dealt with problems earlier). But at least my friends and acquaintances should be made aware of this, so that they do not have to go through the same harassment ever.