Samsung Galaxy Star 2 — service not done properly

I have bought this phone on 18/12/2014 and it has a complaint of out going calls, i have sent this phone to samsung service centre on 05/01/2015. Bu still i didnt get back the phone... When iam calling to them they are always saying that they need more time, now it is about 27 days ago... I need my phone back hope you will take action details of the service centre are Work order number: 12083 Samsung authorised service centre Harmony communications First floor, 429-C21, C30 Lan-ship mall, mavoor road jn, bank road calicut My name: Faisal Address: Narikkuni Calicut Mob no: [protected]