UBER - Charged two times for the same trip

I was charged twice by uber driver and money was automatically deducted from my paytm wallet out of my knowledge without my authorization. So I paid dual for a single trip. When I asked for a refund from uber they said cash payment is done outside there system so they can't refund me any amount of money. They are not giving me driver details as well. They can confirm with the driver as well that he already received cash. If cash payment is out of their system how do they track payment done by cash only? Please help to refund me my money. Attaching the paytm details since I don't have any cash receipt from the driver.