Airbnb Claims They Refunded $264 but My Bank Says No Money Ever Arrived

I canceled a reservation for a May 16–19 stay on Airbnb before the free cancellation deadline. Following the cancellation, the full amount of approximately $264 was supposed to be refunded to my Yapı Kredi debit card. Although Airbnb states that it issued the refund instruction on May 13 and that the payment was processed, no refund has appeared in my account.
I have contacted Yapı Kredi Bank multiple times regarding this matter. My bank has clearly stated that no payment from Airbnb has ever arrived in my account — only a refund inquiry was made on May 13, but the actual refund was never executed. I have also spoken with Airbnb customer service both in writing and by phone, across four separate conversations with different representatives. Each time, I was given the same codes and an ARN number and told to have my bank trace it — but my bank has explicitly stated that it cannot process a trace in that manner and, more importantly, that no incoming payment exists to trace.
My Airbnb account is registered under the name Miray A., and with all the information and documentation available, it is abundantly clear that this refund was never actually completed. I am requesting that the full $264 I paid be returned to my Yapı Kredi debit card as soon as possible. If this is not resolved, I will be escalating the matter to Airbnb's senior management and filing a complaint with the Consumer Arbitration Committee.