I booked an appointment through doc.kz, and the booking was free. After that, the clinic informed me that bookings are made with a 50% prepayment of the appointment cost and that the invoice would be issued remotely. I replied that this had never been the case on doc.kz. The clinic said that these were their rules, that the doc.kz website is merely a service for finding doctors, and that if I was not ready to make the prepayment, I could cancel the appointment. Later I asked whether my appointment on the 21st was still valid and whether I should wait for a reply. No reply ever came.