"Re-arranging weekend clinic appointments"

The provision of weekend appointments is a great idea but sadly it falls down when it is impossible to find someone to cancel and re-arrange an appointment. I can't understand why it's not possible for the weekday clinic staff to make the new appointment. Instead I've been given two telephone numbers to contact myself but are never answered with no facility to leave a message or request a ringback. On one of 8 occasions I tried calling and hanging on waiting for an answer, my call was re-routed back to the main switchboard!! Worse case of going round in circles I've come across. Hopefully someone helpful will see this message and offer assistance.