Southwest Airlines Duplicate Charge

I purchased a Southwest Airlines ticket for the Cancun–Miami route on August 31, which was charged to my Schwab Visa debit card on August 24, 2026. For this same ticket I was double charged, and in addition to the Southwest charge there was a second charge of $439.70 from “Partners on Booking BV Amsterdam.” After noticing the double charge, I contacted the parties involved. Schwab was refunded by Southwest immediately, but the $439.70 from Partners on Booking BV Amsterdam has never been returned. I was expecting this refund around August 27, 2026, but as of today there has been no refund or clear explanation. I request that the $439.70 related to the duplicate charge from Partners on Booking BV Amsterdam for the same Cancun–Miami ticket be refunded to my Schwab Visa debit card as soon as possible, or that I be provided with a clear written explanation of why this has not been processed.