Sixt Did Not Refund My Deposit After Car Rental at Tirana Airport

I rented a car from Sixt at Tirana Airport in Albania on 10.07.2025 through Booking. I had no problems returning the car on July 17, 2025. I was told both verbally and in writing when I rented the car that the €350 deposit would be returned on 14.08.2025. But even though the date given has passed, there has been no refund. I have tried to reach Booking many times about this, but they have not gotten back to me. I also called my bank and was told that my account has not yet received a refund for the deposit. The number for my reservation is 617912667. I paid the deposit with my credit card. I need my deposit back right away and my complaint taken care of.