MyHyundai App Does Not Allow Me to Book Service Appointment

I am trying to book an appointment at the Istanbul Odak Bayrampaşa service center for my Hyundai Tucson using the myhyundai app. However, I cannot book an appointment through the app; I cannot select a date in the appointment steps and cannot complete the process. This problem existed last year and continues this year. I tried the app on different devices and internet connections, but the result was the same. The app exists for this purpose but does not perform its function. If it's not going to work, I don't understand why the app exists. I request that Hyundai provide a solution to this issue and ensure that the app works properly.