Sony India — Sony wireless headphone WI-SP510 / Buttons Rubber bloated and peeled

Address:

P.Saravanan, South street, Nallama Naickan Patty, Dindigul-624003

I've purchased last 04.11.2021 the product of Sony wireless headphone (waterproof) model:
WI-SP510 serial no:[protected] year warranty).
But, that product buttons rubber are bloated and buttons peeling after 8 months. So I'm contacted to Sony Authorised Service Centre (CITY ELECTRONICS PVT.LTD, Dindigul, Tamilnadu).
But they are say's, warranty not affect for this kind of problems and warranty affects inside parts and sound problems only. And they are not taken any complaints.

My doubts is, this kind of problem is upcoming, then why & how you say this product is waterproof?
So please solve this my problem.