Lack of detailed diagnostic tests.
I coughed for over 20 years and was diagnosed with asthma. I went to see a chest physician in London who could not believe I had never had a CT scan - despite having private medical insurance. One hour after having the CT he showed me a lump in my upper oesophagus. After more investigations I had to have surgery in London and the cough disappeared within days. I have written the doctors but did not want to make an official complaint as no doctor is infallible - only God is. My main point is to remind all doctors to use private tests when patients have private health insurance and take some pressure off the NHS. I must have 8 NHS chest x rays over the years but never offered CT.