Sony India — problem after upgrading home theater

Address: Nagpur, Maharashtra, 440015

Website: www.sony.co.in

Self purchased home theater model bdv - n7200w two years back and was working very fine.
Ten days before, on connecting with internet, system asked to upgrade with new version.
After upgrading with firmware update m21. R.0180, the rear surround speakers have stopped working.

Even after visiting of sony service representative and paid for his vising charges the problem is not resolved.

There may be bug in the firmware update m21. R.0180.