"Non starter"

After being referred by my GP I booked an appointment through the online system. I then received an additional (pre?) appointment in cardiology. As I was unable to make the date given I called to let them know. Over three hours I called nearly 60 times - mostly getting an engaged tone when I finally did speak to someone she immediately said "please hold" and I was left on a blank line for 10-15 minutes ( this happened a few times). I finally had a conversation with an administrator/receptionist who said she would pass the message on and I would receive an alternative appointment. I have now received a letter saying I missed my appointment without letting the hospital know and will be discharged back to my GP! So the outcome, after months of waiting and suffering with very distressing palpitations, is that I now have to start all over again. This level of incompetence from staff at Whipps Cross/the appointments system is outrageous, and I can't even get through to anyone to make a complaint!