Sony Music System — Pathetic Service Provider

Dear Sir,
Having a NUMBER 1 image in mind of SONY Corporation throughout the world I purchased Sony Music System MHC-GNZ8D, Serial number 6115388 on 27th Aug 2006. And from then till today (more than 3 years) the Music system performed beyond expectations in all aspects. The performance of the Music system converted my “CONFIDENCE ON SONY” to “RESPECT FOR SONY”.
And I carry forwarded the respect by recommending Sony Products to all my near and dears. The sale of atleast 3 Handy cams, 5 cyber shot cameras can be attributed to my feedback along.
But 2 months back I started facing some small problems in the system like Key operation hard, Key malfunctioning and Disc Exchanger malfunctioning, so I submitted it for servicing to one of the Authorized service center in Aurangabad and the details are as follows
Date of submission: 17th Oct 2009
Challan –CUM- Dispatch Note number – 3077

Service center Address is
Creative Electronics, LR 04, Kuber Avenue B,
Opposite Hotel Athiti, Jalna Road, Aurangabad-431005,
Maharashtra.

They replaced some parts like Optical Block, Motor, FR Belt, B Belt and switches and charged me Rs. 1786.
They rectified some of the problems and “AS A BONUS ADDED SOME MAJOR PROBLEMS TO MAKE SONY PROUD OF THEIR SERVICE”.

The problem in the system is that the sound output of system is not increasing once it is increased from 25 to 30 level.

And since 17th Oct 09 when I first submitted the system to service center I am struggling to get my system rectified.
I have visited them 15 times, made them around 50 calls and submitted the system 3 times (Can be cross checked with Job card available with the service center), but both of the problems still persists and the system is lying at my home as it is.

My respect scattered after this incidence and I was not able to believe that “SONY” talking of customer relationship management, one-to-one marketing, most valuable customer, and customer-centric focus.
I cannot believe that SONY can provide such a pathetic service to its customers.
I am not able to understand how you all manage such a world class service ???

I am still writing this with a hope that my problem will be taken care. I request you to please look in to the matter as soon as possible.