PIP Assessment anomalies

Hi there
I was on the highest rate DLA indefinitely since 2007 and had a PIP f2f Assessment in September. The whole thing was a shambles, I felt railroaded into answers and kept being told ‘keep it simple, they want it kept simple.’ In the end the manager was called in as I was crying and shaking uncontrollably, so much so that I could barely sign my name on a document given to me allowing the info brought in in the day to be sent to the DWP.
However upon reading the Assessment Report, the Assessor states that I was ‘normal manner, not agitated or tense throughout’ ‘no anxiety or trembling.’ There was no mention of the upset, nor of the Manager being called in. The report also refers to a physical assessment that bears no relation to what I can actually do eg leg/hip/neck movement, and outlines tests that I would have had to stand up for, and lie down for. I remained seated for the duration of the assessment.
Also it states that I passed an MSE with flying colours, and my husband and I know that I was not asked any of the relevant questions re this. As medication fog is one of the main side effects I have, this is important.
I complained to IAS immediately regarding how the assessment was carried out and wrote a letter of complaint to them again once the Report came through. The disparity between what actually happened and what was reported is truly shocking.
I spoke to IAS Customer Services yesterday and they informed me that the Assessor and Manager have replied to my detailed letters of complaint and stand by the Assessment. However, because the Manager being called in was not referred to in the Report, but the Manager had logged he was called in, as well as numerous other untruths that are easily provable by my specialists eg Range of Movement, muscle weakness and wastage, I am wondering where to go from here, and is this Assessment problem normal? The DWP have downgraded my award from Higer Rate on both to Lower Rate on both which isn’t borne out by my condition, (which orthopaedically is extremely rare and is no longer carried out as was pointed out numerous times during the Assessment and in my application (so rare that when I first had it done in the 1980’s a book and video were written about me) as have my health professionals.
The hardest thing to read in the Assessment is that I need reviewing in a year, despite the fact my condition is degenerative as has been noted in all of my supportive medical documentation. Is the fact that physical/mental tests attributed to me on the day were simply not carried out, nor am I physically capable of them mean I can appeal this, and is it likely that Mandatory Reconsideration will fail despite all of this, and I will be forced to go through with a Tribunal?
I can understand that there may be differences of opinion or nuance in how an assessment is conducted but the level of falsehood has knocked me for six.
I would appreciate any advice you can offer.
Many thanks

Thank you so much for your advice Gordon.
Yesterday IAS told me that my complaint was with their expert Assessors Dept and that they will write to me in the next few days.
However we only realised last night when googling what ‘straight leg raise’ (as detailed in my Assessors Report) was, and that I would have had to be supine for this and for the hip flexion tests, yet I remained seated throughout. Also given the fact that I am physically incapable of the reported results, do you think I should call IAS again and inform them of this new information before they make their final decision re my complaint? (My Chartered Physio agrees that I would not be capable of their results.)

And please could you let me know what an MSE consists of. It is mentioned at various times within my Report but we genuinely cannot remember being asked any questions that would refer to memory etc. I mean I know my memory is shot to pieces due to heavy medication but really...
Thank you again.

Thank you again. Is it possible to have ‘straight leg raise’ and ‘hip flexion’ tests whilst remaining seated? Perhaps it’s better if I see my physio and get her to go through the report’s assertions one by one. I can then use this as a basis for my appeal?
Regarding the MSE, I do remember pinching the Assessor’s hand, but had mistakenly thought MSE refereed to Mental or Memory as opposed to Physical tests.
Thank you very much for your help. This whole process is overwhelming.