Apple India — Iphone11, 128 GB

I bought an iphone 11, 128 GB on 20th October, 2021. The phone started having battery charging and drainage problems from 15th September, 2021. It would take around 3 hours to charge and would get drained in 10 to 15 minutes. I called up the retailer on 1st October, 2021 and also sent them an email and they asked me to contact Apple support. I called up Apple support and explained the whole issue to a lady there and then again to one Mr. Rony Fernandes and they asked me to go to their hardware store near my place in New Delhi. I went there and they ran a test on my phone battery and said that it was alright. They did not mention anything about the charger. I too didn’t because I was not aware that the charger could be faulty.
Then I went out of Delhi for work and saw that the phone was not charging. The battery charging would go on and off. I had to use a borrowed charger. I came back to Delhi later and called up Apple support at least 5 times. I would keep on holding and the music played for more than 15 mins. Ultimately when I was able to talk to them, one Ms. Maria Janet guided me to the same hardware store. I said I just wanted the charger replaced. She told me to get in touch with their senior on Apple support once I was in the store and connect him/her to the customer service person at the store and that the issue would be resolved immediately, which I did today. The Apple senior spoke to him but could not resolve the issue. They refused to replace the charger on the pretext that the warranty was over now. I have been complaining since 1st October and since the warranty has ended on the 20th October, they are not replacing.
This is so unjust on the part of Apple. First, they provide a substandard accessory and then they refuse to replace, even though the issue had been reported 20 days before the warranty ended. Apple, being an internationally reputed brand is acting petty with a customer who has been using their phones since long. Is this expected from a brand like Apple? They have priced their products so steeply because of their brand name, though technically comparative phones cost 1/4th of Apple’s prices.
I request they replace my charger asap.