Paytm — Cashback not credited on buying IPhone 6S

Address:	Mumbai City, Maharashtra, 400079
Website:	Paytm.com

I had bought IPhone 6S 64GB on 21/12/2015 and I was promised cashback of Rs. 10000 and I still haven't received it. I raised a request to upgrade my wallet but no action has been taken from their end. Whenever I call their customer care number, I cannot get in touch with their customer representative. In fact, there seems to be no way of getting hold of their customer representative which I think is completely wrong.

I would like to get that 10000 cashback that was promised to me. Also mainly I want a customer representative to attend calls when someone calls their customer care number.
I have attached the invoice here. Kindly go through it.