OnePlus India — Oneplus 8 / asking for service charge for a defect caused by software update.

I have updated my oneplus 8 mobile to Android 13 recomended by oneplus. after the updation a slight line appeared on my screen and it suddenly got worse and my display damaged completely. i've contacted customer care and they told me if i send my phone to oneplus service center they will repair it for free even the phone is out of limited warranty (which my device is) and is free of physical damage. so i sent my phone to oneplus service center using their pick up and drop service. when i gave them my phone it was completely free of any scratches or physical or any other damages. now they have contacted me saying the service will cost about RS 14000 because they say my device has physical damage (which wasn't there when i gave them).

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