Xiomi India - Denied repair in warranty period

Dear Sir/Madam,

I purchased a redmi * phone last month. After using it for ** days, it is showing a display issue and not working properly. I went to MI service center Pimpri, Pune. After checking the phone they were saying it is internal damage and not under warranty and told us that the phone might have fallen down. I want to tell you firmly that it does not fall in these ** days and there is no single crack or even hairline crack on the phone. Phone body is also intact.

If it is fallen down it must have some damage to the outer body. I am feeling cheated by the company after giving **** Rs for a phone and giving preference to MI over other smartphones.
Please help me in resolving this issue as soon as possible.
I am attaching a screenshot for your reference.