Cartrawler Won't Refund My Car Rental Fee, Unresponsive Support

I rented a car through Cartrawler, but I still haven’t received my refund. I’ve sent multiple emails with no response. There is no contact number, and the person I spoke to on WhatsApp couldn’t communicate properly, using translations to reply. I booked this service through Pegasus after buying a flight, and now I regret continuing. I had to change my flight plan and emailed them to request moving the rental to the next day. For this simple change, they wanted to charge me ₺2,700 on top of the ₺1,800 I already paid! When I tried to cancel the reservation altogether, they asked for ₺4,000. This is an outrageous system, and I’ve never seen anything so absurd. I demand my refund and a reasonable solution immediately.