Yatra app - refund not receive from yatra app

I have booked bus ticket last month after that on the date of journey **th Jan I know that my bus ticket cancelled by bus operator... after that i have sent mail to yatra to refund my amount but still now I didn't received any amount from there side they want denial letter from bank i have already share my passbook detail till **th feb date to check but they want denial letter in every mai they asking same thing.... please help me to get my refund amount at earliest