Groupon India / Nearbuy — Money not refunded for expired voucher

Address: 500034

Website: www.nearbuy.com

I had purchased a voucher from Nearbuy (formerly Groupon India) website. The voucher details are as follows:
Restaurant: 36 Chhattees BBQ Restaurant & Lounge Bar
Offer 3 (Early Bird): BBQ Buffet Dinner + Soft Drink
Voucher Id: NBNGN7NRB2YCRT
Purchase Id: 418728
Validity From: 23-Nov-2015
Validity To: 22-Feb-2016

Due to some personal reasons, I could not avail the voucher before the expiry date i.e. 22 Feb, 2016. Almost a month after the voucher has expired, on 13th March, 2016 - I checked the Nearbuy website and while going though all my past transactions – I observed this particular voucher had not been utilised/availed by me and in order to go through the voucher details I clicked the redeem button. Now, when I called up the Nearbuy executives for refund - they are saying they cannot refund the money back to me as I have clicked the redeem button (which, as I said earlier, is after the voucher has expired) and that they have released the money to the merchant (i.e. the restaurant). In this regard, I want to register a complaint against Nearbuy as to how can they say they cannot refund the money back to the customer (when the voucher itself as expired; after which the voucher is deemed as void) and then how can they say they paid the amount to the merchant.