Living with visual problems, Discovery wont pay!

I am very angry and confused regarding claims for my visual therapy. I have had a long standing visual problem. I have a functional squint which I have had since birth but was only discovered when I was 25 years old. It first started giving me REAL problems just after I turned 30. I started a visual therapy programme with Eyetek at the time. This therapy was very difficult at times but after a year, my visual skills had improved significantly. In March this year my squint completely broke down again- I had complete double vision. After tedious examinations from the neurologist (with an MRI) and then an ophthalmologist, and then an orthoptist, have ended up back with Eyetek- more visual therapy. BUT Discovery has now refused to pay for the visual therapy claims from Eyetek when they did in the past? The most important issue I want to raise with Discovery is that I am currently driving around with double vision. What happens if I have a car accident and hurt someone, or worse....what happens if I kill someone because of my visual problems? This is something that is causing me a lot of anxiety. Visual therapy is NOT an optical benefit!!!