PIP Changes in PIP Law

I received a letter from the Dept of Work and Pensions regarding the changes in PIP law and I would like them to consider and look my social support that I had in the past regarding my mental health problems that I had from April 2016 which they dismissed then when I made my claims back then and would like to know how I begin to write a letter to ask them to look into this and what happens when they do this and what exactly are they looking for and considering as evidence as I did have depression and still have since 2016 I just do not know where to start, this letter is making me anxious and has raised my anxiety I'm really worried about it, please help

I

I'm afraid we cannot help you with the letter as we have no idea whether you met the criteria in 2016 or not.

The criteria you are being asked to meet are described in our PIP claim guide; the Mixing with Others activity, Descriptor (c).

Gordon