Hyundai Motor India — Battery Life Elite i20

How can a car bought in March 2018, suddenly have a battery level below 75% by December 2020. On top of that it is a petrol car which is driven daily, completed 25000Kms so far. It is mostly used in city travel and occasionally out of town.
Service charges are exorbitant and we expect a smooth experience later on. However in servicing, I had few nuts and bolts tightened because honestly my car was not giving me any problems. The bill handed was 9.8 grands and the very next day, I have a flat tyre. Reason being that from where the air gets filled, it was broken. So what was checked during servicing? I honestly will not be visiting any Hyundai service centre anymore. Horrible experience.