Xiaomi India — Mi 4i Sound problem

Address:

Valsad, Gujarat

Hi, I have purchased Mi 4i mobile from Flipkart before some days. I am facing problem in sound quality. It is very low sound. When i start song that time sound is good but after that give low and low. I have checked with all song in default sound player and also in Google Play music. Same thing checked in video song but quality is very poor. Also facing problem in calls. Sound is listening very low during calls. I am running on latest os version and it is upto date and installed all latest paches. Is it bug or hardware problem or manufacture defect? Please tell me now what to do. You are going to call back the mobile and send the replacement or issue the upgrade package.