Confirmed tickets are invalid after paying in full

I tried to book tickets through Yatra.com. I thought everything was fine until at the end of the booking process the system said tickets were not booked. I went to a different air ticket site and bought my ticket there.

I forgot about the incident until I saw my bank statement with a transaction from Yatra.com for the tickets that were not booked.

I contacted Yatra.com and they told me the money will be credited back to my account in a week or or. It's been three weeks and I am still missing this money on my account.