Lenovo — repairing of phone after software updation

Address:	Vadodara, Gujarat, 390007
Website:	Lenovo.support.in

On 6th of May I had received an updation in my phone for software. I did that from my phone's internet, but after that my battery was not charging properly, it got drained out soon and my phone hanged alot. So on 7th evening I submitted my phone to lenovo service centre in Vadodara and they returned me my phone after 2 days stating that the problem has been solved. After using it for 2 days I resubmitted my phone as the problem pertained. On 11th evening I had submitted my phone in service centre and have still not received it back. I made lot of phone calls to service centre and customer care but even after 20 days no one is responding neither giving me my phone nor replacing it as it is still under warranty as I had purchased my phone only this February. Please help me or I need to file a case at the consumer forum.