Refund Not Issued For Cancelled Reservation

I made a car rental reservation with the number 17BB1D460CD6 via Obilet using a coupon code that had been assigned to me, and I paid the price difference above the coupon amount with my credit card. Due to a change in my plans, I had to cancel this reservation. After the cancellation, the amount I paid by credit card was refunded to my card, but the value of the coupon code I used was not refunded to my card and no new coupon was defined for me. As a result, I lost the monetary value of the coupon although the reservation it was used for was cancelled. I request that the amount corresponding to the used coupon code be refunded to my credit card or, alternatively, that a new coupon code of the same value, valid for use on Obilet, be issued to me so that my grievance can be resolved.