I've an issue with one of your partner called Vayama

I've reserved a flight ticket from booking and booking forwarded my request to Vayama, then after I confirmed everything with Vayama about my ticket and completed the payment process, they sent me the below message.

They refunded the money less than what I paid, and I had to book another airline ticket at a higher price.

Their message:
 

Dear Milad Ibrahim,

Unfortunately, your booking request on VayamaNonUS failed. During the booking process, the airline provided us incorrect availability for the price you selected, regrettably we were unsuccessful to rebook your seats.

We have cancelled your booking request *** and refunded your payment of €1,301.00.

Because of the processing time required by the banks and credit card companies, it may take 5 to 10 working days before you can see this payment in your account. Unfortunately, we cannot expedite this process due to external parties.

We apologize for the inconvenience.