Consumer Redressal

My self Emamul Haque. I have taken karbonn A21 in July 2013. From day 5th of buying I m facing hanging issue and battery discharge issue. Maximum time I have to put my phone on charge. Once full charge its gets discharge suddenly. I have taken 3 months follow up from karbonn service center vashi for replacement of my battery. Every time I was told next week new battery will. After 3 months he tolde I have shut down karbonn service. Then I went to karbonn service center thane and now its more than two months but did not my battery. They say karbonn is not sending battery. when i m aaking to give my battery request number they are saying we cant provide its compny rule. call to customer care. their customer care never2 did respond in this 8 month every alternate day i m trying to call them.Now I m totally flustreated with mobile hanging and battery discharge issue. They r just casually doing time pass. I have lost my salary by going there now and then. I have written more than 100 emaila to the email ids given in karbonn website but not got reply. What should I do now?. I m now feeling cheated from day 5.