PIP review without a form?

Hi,

I am a little bit confused, by how my PIP review looks.. from what I have found, I should receive a form, and then eventually have and assessment.
In my case, I just received a letter saying that someone would call me, I did not have to fill out any forms. When the date came, a lady called, we went through all of the questions, at the end she confirmed that “it looks that you are getting the correct rates”. And I thought that was it. I thought THAT was the assessment.
But a little over a week later I got a message from Independent Assessment Services that they would look at my case.. now, another week later they booked me in for a face to face assessment..
I am just wondering if anyone else had the review done this way? To me it looks a bit strange, that at no point was I sent the form to fill out like everybody else. And now I basically have two assessments.
I won my award at the tribunal the first time, but I don’t know if I can go through this again, it was exhausting.

Thank you, any suggestions as to what to do with it will be appreciated. I am wondering how can this be fair to proceed with a face to face appointment when I haven’t had a chance to submit any evidence or even explain my difficulties.. and if they make their decision this way, maybe it can be a basis to dispute it. I have had very bad experience with the whole process before so I am not even expecting they will make a fair and informed decision, especially that my conditions are widely misunderstood (CFS/ME anxiety and depression).