Evidence for PIP application

Hi. I wondered if anyone could help (or perhaps commiserate with me!) I'm in the process of having to apply for PIP despite previously having a lifetime award of DLA. The guidelines say that you should provide evidence from all of your health providers as the assessors may not contact them themselves. The thing is I have a lifelong complicated disability (a birth defect) and I have several consultants. I wrote to them over a month ago to ask for a letter of evidence/support, however they are refusing to give me a letter and keep referring me back to my GP. I very rarely visit the GP (if at all) and all of my healthcare is provided by specialist consultants (and has done so for the last 44 years!) So I now have no evidence at all of my lifelong visits to them! What should I do? I feel it's really unfair as I'm now suffering great anxiety. My GP could write a letter with all of my medical conditions on it, but she doesn't have any knowledge of my past problems or how they affect me on a day to day basis.

Thanks

Cat x

Also I think you can ask them (PIP) to look at the info from your DLA, is that right Gordon?