Hi David
If you have been receiving PIP for a number of years, I assume that at some point you sent in some evidence of your diagnosis or someone would have queried this before? So if you have previously sent them information, then you should point it out to them, because it must be on the system. If you can get an up-to-date letter from your GP, do so - but not all doctors are willing to write letters.
BIS
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
