Paytm Mobile Solutions — want my money refund

Address:

Jamnagar, Gujarat, 361006

I purchased mi a2 mobile from paytm. My order id is [protected]. I got defective mobile from paytm. I requested for return item and refund my money. They collected mobile from my home but the problem is that earlier i got cash back of rs. 1620. This cash back they do not give me at now. And i can not cancel the order from paytm's website. No buddy picked up the phone in paytm customer care as i tried daily.

I don't know from where i founf the solution for this problem. Please help me in it. I want cancel my order now.