A private MPV from Hong Kong to central Shenzhen starts from RMB 700 / HKD 810 per vehicle, one way. If the clinic can give you a reliable finish time, the return can be booked as a second leg. If treatment may run over, book the outbound first or compare it with up-to-10-hour day hire instead of forcing a return time.
Before you confirm the car, ask the clinic for three things: the check-in time, the likely finish window and whether an adult companion is required. Those answers matter more to the transport plan than the name of the treatment.
