public void MarkAsSeen(int notificationId, NotificationType type)
        {
            switch (type)
            {
            case NotificationType.Referral:
                _referralRepository.MarkAsSeen(notificationId);
                break;

            case NotificationType.TestResult:
                _testRepository.MarkAsSeen(notificationId);
                break;

            case NotificationType.AppointmentRequest:
                _appointmentRequestRepository.MarkAsSeen(notificationId);
                break;
            }
        }