"Long wait for diagnosis and cancelled appointments"

I was initially referred by my GP in December 2012 and got my first appointment in March 2013. I was given a shock initial diagnosis of Parkinsonism in the last minute of the appointment with no information given, other than that I would be referred for a DATscan and have a follow-up appointment in June. I eventually got the DATscan in April (the initial appointment letter hadn't been sent out and I had to chase that up through PALs). At the end of May I rang PALs again to chase up a follow-up appointment and they arranged one for me for July. A week later and I have had a letter cancelling that appointment with no date given for when I will get an appointment. In the meantime I do not know what is wrong with me and I am becoming increasingly disabled - I cannot walk more than 20m and that takes me over 2 minutes, it is affecting my breathing and swallowing and I am losing weight as I find it difficult to eat. I am in danger of losing my job and to be honest just feel suicidal. The NHS constitution states that patients should start treatment within 18 weeks - it has now been 28 weeks since referral and I haven't been given any information, never mind started treatment - over the past 2 years I have been passed round consultants and still have no answers, yet there seems to be nobody taking any responsibility - I have had to chase for everything that has happened. My quality of life is becoming worse by the week and it just doesn't seem worth going on any longer. I provided a list of what had happened and my symptoms and how they have progressed for the doctor I saw at my appointment and it didn't even get read. I am completely fed-up of the whole system.