Refund against delivered/returned wrong product

I purchased (Cash Rs. 699 On Delivery) a Power Bank (Ambrane) by on-line shopping from snapdeal on 9th September 2013, whose order id is 1245083898. They delivered used product. Then as per their policy i returned that product via courier, pick up arranged by snapdeal. After that they initiated refund process through NEFT. They mailed me on 18th October that they did refund on 17th october 2013 in my PNB A/c No. XXXX2037, IFSC Code: PUNB0388900 whose Refund transaction id. is P13101792624401. But still i haven’t received that refund. When i contacted my bank they told me there is no transaction has done with this transaction Id.When i called snapdeal regarding this. They asked me for bank statement. I mailed them on 19th Novmber, they told me they will give response with in 48 hours, but they didn’t. Now every tim when i call them they tell me that i am forwarding the status and we will respond with in 48 hours.
Please guide me, what to do now?
Regards
Rahul Kumar
M: 09625265828
Address:
F1, Knollswood
Shimla-171002