Rentalcars.com Car Rental Overcharge Problem

I booked a flight with Sunexpress Airlines for Antalya to Gaziantep, and Diyarbakır to Antalya return flights. During this process, I accessed car rental services through the app and made a transaction. However, after the transaction, I didn't receive any confirmation or receipt via email or message regarding the car rental. Upon seeing a charge from rentalcars.com on my credit card, I tried to cancel the transaction by reaching out to 1) Sunexpress Airlines and 2) the service provider, Garenta. However, the rental company informed me that the transaction cancellation should be done through rentalcars.com (Booking) and could only be canceled from there. Despite not having any confirmation information, when I tried to access the reservation through rentalcars.com, I couldn't find it (I confirmed with Garenta that such a reservation was made). It seems that rentalcars.com made a reservation and charged me without any communication or notification. As rentalcars.com doesn't have a customer service line, I can't reach them to cancel the reservation. Additionally, Garenta states they can't cancel the reservation either. Sunexpress Airlines has yet to respond to the matter. It's unbelievable that two reputable companies Sunexpress and Garenta are associated with such an irresponsible service provider like rentalcars.com. Local service providers don't even bother reaching out to address customer satisfaction issues. What can I say? Enjoy spending the money you took from me for a service I didn't receive and won't be using...