Yatra - Yatra not refunding money

I made a booking to travel from Delhi to Pune for **th June **** but couple of days before travel I noticed that PNR on airline shows the date of **st June. I didn't request any change so I was surprised to see this. First Yatra.com was not available on the phone to discuss and help sorting this issue urgently so I had to finally book another ticket with some other airline and filed a complaint to Yatra via email. After two months of continuous follow up Yatra says that someone seems to have called airline and changed the booking over the phone therefore I should speak to airline and they will not refund my money. Without any evidence they seem to have come up baseless reason and not refunding my money. Such a pathetic service!! I wonder why did I pay the conveyance fee to Yatra and why Yatra should not refund my money.