"Had the misfortune of seeing the same Neurologist..."

I saw a Doctor from The Walton Centre back in 2012 who said I was too young to have anything wrong with me and one week later I found out from my GP my B12 level was 50. I am still having symptoms of nerve involvement so I got reffered back. Yesterday at my appointment I was told I fall into the 70% that will not get a diagnosis as it is just symptoms and not a nerve condition. Am I going to believe that from the same neurologist who couldn't diagnose me the first time round? I think not. I know my symptoms are down to B12 deficiency/pernicious anaemia as they were relieved with my loading dose injections. Not to mention all the evidence I have. People do not have symptoms for no reason and he is dismissing 70% without a diagnosis. I have been offered to go for a lumbar puncture but he has told me he won't find anything so I am basically being dismissed. There are new bcsh guidelines out and this neurologist obviously hasn't read them.