Hertz Deducted Money From My Account After Rental Without Reason

I rented a full package car from Hertz Charleoi Airport, Belgium, between July 13th and 17th. When I returned the car, they confirmed everything was in order. On August 7th, a €90.5 deduction was made from my bank account, and when I asked why, they couldn't explain it. Despite providing me with information about the date I rented the car and the license plate number, they're still asking for the reservation. They're completely unhelpful and don't even know why they're making the deduction.