I only just had my PIP claim awarded last month at enhanced rate for both elements. I'd previously applied 3 years ago (just before my Autism diagnosis) and had an absolute battle just getting daily standard care and no mobility. Went to tribunal and they wouldn't award any further, so put in change of circumstances once I had my official Autism diagnosis. I shouldn't have needed it, as my issues are exactly as described first time round, and meet the descriptors. I just don't think they believed me without the diagnosis.
To be transparent, I also have a connective tissues disorder, so I have physical health / mobility issues too, therefore it's because I have a combination of issues that impact me, that I've been awarded.
Second time round, I knew better how to fill the form in and deal with the assessment (I refused a face to face and was given a telephone assessment instead) I've been given an indefinite award, with a possible review some time after 2034.