First, verify that the second debit isn’t merely a security hold or authorization; Sixt indicates that holds usually clear within 5–15 business days following the return.
If you suspect a genuine duplicate charge, retain the card statement that displays both transactions.
Collect your rental invoice(s) to review the details—Sixt allows you to download invoices from its self-service portal, typically accessible 2 or more days after your return. Be sure to look out for additional charges such as fuel, late returns, or cleaning fees.
Contact Sixt support to report the duplicate, and ask for a billing correction and refund. You can either submit an invoice query or utilize the live chat option. Provide the booking number, the dates for pickup and return, along with screenshots of both charges.
If Sixt fails to issue a refund quickly, consider filing a complaint on Xolvie to reach out to others and seek assistance.
Related Complaints
I Face a Refund Delay from Sixt — €339 Tire Replacement Still Not Paid After Four Months

On June 20, I rented a fully insured car from Sixt Switzerland. While driving in the Netherlands, the tire burst, and when I contacted Sixt Germany, they instructed me to pay for the replacement first and assured me that the amount would later be refunded. I paid €339 for one tire and submitted a co...