If you have a query regarding an appointment then you should contact that hospital directly. You can usually find their direct contact number on your clinic letter on the top right hand corner. Or you can ring the hospital directly and ask the switch board to transfer you to the appropriate consultant secretary.
If you have a query with regards to booking an appointment through the Choose and Book system then you can phone the Choose and Book number which you will have on the paperwork you received through the post. If you still have a problem you can speak to the Practice Secretary directly or ask The Practice online.