Samsung - Money not being refunded

I had purchased the mobile on **th august and got delivered by **nd august, in two days the phone started to switch off so I went to service center. I got a DOA certificate from the service center and was told if I don't get the phone replaced within *-* days I will get the redund.
It's been more than *.* weeks I haven't got any positive response from Samsung. Some customer executives call and say phone will be replaced whereas some call and say I will get the coupons of the same amount I bought the phone for. Well if refund can't be done then I can't continue to seek services from this brand as it's a famous and old brand of our country but giving pathetic services now.