Xiaomi Redmi 11 Warranty Coverage Denied

I purchased a Xiaomi Redmi 11 phone, and it is still under warranty. When I searched for 'customer service' on Google, I came across a firm named Bestech that claimed to be affiliated with Xiaomi, so I mailed them my phone. Two days later, they called to inform us that due to excessive button pressing, it is not covered by warranty and thus not repairable. They also requested a fee for repairs and maintenance. I asked them to return my phone without taking any action, but this time they charged me for return postage. They are not delivering the attention required by the warranty. I'm not sure how pushing a button may void the warranty. This is why I am complaining about Xiaomi.