Xiaomi India - Xiaomi India Warranty issue

I have purchased Xiaomi Redmi ** Prime **** mobile on (**-Oct-****, the phone had got shutdown and don't know the reason. I tried the charge the phone where it was not responding and was not getting charge.
On **-may-****, then I took it to near by Xiaomi service center [Tanny Communnication, ***, *nd floor, Mahek Icon, Beside Sumul Dairy, Near Railway Station, Sumul Dairy Road, Surat, Gujarat ******].
After they inspected the mobile they had sent me message on whatsapp
[
Dear Mi fan,

Your Mobile Repair job sheet number WXIN************* has been repaired and total estimated repair cost is *.*. It will be delivered to you by ****/**/**.
You may reach out to us on ********** for any further assistance.
]

i got the above message After * days they called me and told me If you have opened this mobile somewhere, then I said that for the first time, there is a problem with my mobile,
so I have come here and it is under warranty, so why should I open it somewhere?
they told Your mobile will not work, now the company has made it out of warranty this mobile is opened somewhere.
When I called Mi Customer Care for the last time, they are telling that the phone will not be made under warranty you have to pay charged.

I am very upset since day please help me. i hope i get a solution soon.

Thankyou