Karbonn — Service time

I submitted my Karbonn A15 handset to their authorized service centre at Dwarka Mor, New Delhi on 16th August 2013. But there is no update about the current status of the handset. They are telling that it is sent to company for repairing. I talked to Karbonn customer care, and they said yes they had the handset but they do not know when will they return as it is in reparing process. I emailed to the Karbonn support team but they too have the same answer. Also my set was serviced by them for the same problem in April 2013. That time too they had taken more than a month to return it back. From then on it was continuously showing the same problem. As the handset is in warranty period, they are just killing the warranty time.So their sole intention is to kill my warranty time. Please take some action. I am unable to communicate with my clients, and so I have great loss financially. Disputed Amount: 15000