"Doctors surgery always waiting one hour for an appointment"

Every time I visit my doctors practice, Chislehurst Medical Practice I am made to wait over an hour for my pre-booked appointment. It is deeply frustrating as I take the time to book an appointment and arrive on time and no matter whether it's first thing in the morning or the evening I have to wait an hour. How can they be managing their appointment booking system so badly? I have to take time off work to visit there and would just appreciate it if it wasn't wasted in a waiting room.