Lenovo — mobile phone listening sound issue

Address:

New Delhi, Delhi, 110068

Dear concern,
I purchased lenovo power k6 mobile on line from amazon. After 10 days of working i found that listening quality of sound was not proper. It cracks and going slowed down and some time not audible at all. While it is working good over speaker call or on earphone. I visited twice at your laxminagar service center delhi. They told that i changed the mike and now it is okay. But still i am facing the same challenge. Requesting your support to resolve this problem permanently as it is buying time and money.