Flipkart - Double amount paid to Flipkart for the same order

I had ordered Mosquito net (Classic) for Rs *** through Flipkart on March **th using Google pay. Double transaction of Rs *** has been made to Flipkart as attached bank statement. I cancelled the order immediately when the amount was charged twice. Refund for one transaction of Rs *** was received. I am complaining to Flipkart from March **th and they promised that the other amount would be refunded latest by *th April. But now, Flipkart says their system does not show that duplicate transaction happened.
SBI Bank needs a reference id for the claim back. GPay does not take any responsibility.