"Awaiting results of a scan and appointment..."

I have heart disease and had various operations. I last saw my cardiologist in July 2014. On their written instruction I had a scan in March to check on my dilated aorta root and replacement heart valve. I asked their secretary about the result and was told I would get it in August when I had my next appointment with the cardiologist. A week ago my appointment for August was cancelled due to "unforseen circumstances". A further appointment was offered in January 2016. 5 months ahead and 10 months after the scan! In the past week have rung the cardiologist's secretary and left 4 messages on their answerphone for a return call to try to establish the results of my scan etc, but I can get no response. I am not in a critical condition - at least I don't think I am, but without the result of the scan who knows or indeed cares? How do I get a response from either the cardiologist or their secretary and who do I complain to about the apparent lack of care or interest please?