"No letter of appointment and no response"

Visited a dermatologist with my daughter after being referred by a paediatrician. Six months ago I was told that she would have a six month review appointment. I rang today as now it has been more than six months to be told that her appointment had been missed although I had no letter or telephone call telling me when this appointment was. I'm then given a number to go straight to the dermatology department, I ring for 3 hours straight and no one answers. I have left a message and if I do not receive a call back I will be going up there personally to get them to make another appointment.