Paytm Mobile Solutions — Did not get cash back offer by paytm/uber

This is in reference to a trip that I booked through uber on 21 Oct, 2016. I paid through paytm. I received a message for the 50% cash back on payment through paytm. But I have not received the cashback yet. I contacted uber but I have been asked to contact paytm for the same. I contact paytm multiple times but there has been no satisfactory response from them. I even dropped a message on facebook. They ask for the details but never come back with the resolution. It's has been more than two months but I have not received the casback yet.