Xiaomi India — bad working of mi 4i

Address:

Surat, Gujarat

When i call someone or someone call me, screen gets black and we can't do loud speaker or any other changes. And if i click power button, call gets cancelled.

Please give me another phone, because this is second time my phone has been working very poor.

Or else i will give it's worst review and never buy another phone.

Please solve this problem soon as i have been facing this from long time.