Yatra.com — refund not received yatra.com not processing refund even after refund request

My parents return flight was cancelled by singapore airline. I emailed to yatra.com for processing refund. Return flight was on june-24, today its almost one month, but yatra did not processed my refund request. I emailed them around 20 times for refund. Yatra reply is same, we processed your request but singapore airlines has not processed refund. So, i asked singapore airline for status. On july 22, singapore airline response says they did not received refund request / documents from yatra.com. So, who is to blame. Never ever use yatra.com for any services. If you email and tweet, they will say social media will respond and finally, you are not able to get response from anywhere.