faulty handset not servicing

I have a micromax set which keypad and scroll stoped functioning 5 months ago. I submited it to my nearest micromax service center on 4th july 14. They told me for replacement with a new set if they can not solve the issue as my set is within warranty period. But its been almost 4 month over I did not get any service from them. Every 15 days they are asking to wait for another 15 days. I am totally disgusted with their response so writing to you. So my humble request to you to please take some immediate step if possible. my handset and complain details is as follows.

model no. Q76 micromax
Imei no. SERMOB0234
service center name : M/S Sabsonic , kolkata 700059
req no. R1407FWB10692953