Consumer Redressal

Sir i purchased karbonn mobile Model no-A15, IMEI NO-911244651140552 and TIN NO-06321220718 and CST NO-06321220718 from croma retal store in faridabad.I bought this mobile 4 months ago, and since then i am given the mobile 2 times to service. They take the mobile saying that next time it wont happen and when they give the mobile its the same outcome. Mobile hangs, applications not working, internet not working properly.I am fed up of all this I cant deal with them anymore. Please kindly take some quick action so that the coustemer service deals with all their clients safely . I had also wriiten an e-mail to the head office but from there also i did not recieve any reply. I request you to kindly take some stringent action.