Consumer Redressal

I bought a karbonn samrt phone (A 16) 7 months ago. But I hv some problem in touch while using the phone. So I contact my nearest karbonn mobile's service center which name 'Mousomi sales & services'. The service center's excicutive told me that I have to give them the mobile for some days to solv the touch problem.and I do that...they said me they returned my phone within 21 days...I send my phone on 10.11.2014 to servicing..but they till not give me my phone...I call them twise in a week but i got some new excuses from them evry time when I call them..I also cotact the karbonn head office in kolkata but they will also give me some new excuse. It's near abot 2 moths and I couldn't get my phone back..plese do somethin urgently plese.