Cancelled Capita Assessment

Hello all,
Was due to have home assessment by Capita this week.
They have cancelled "oh surprise"
This has caused overwhelming distress to the person I care for.

I was also told when I queried about reasons a paper based assessment was not applicable in this case, that it could be but it would delay getting a decision by months, also this type of assessment would then require further evidence, how a telephone advisor could qualify this is beyond me.
I was able to ask this question due to access via this site to - the
PIP Assessment Guide - Part One - The Assessment Process

Specifically - Cases that should not require a face to face consultation. Section 1.5.4

I also am notifying the DWP in writing about the cancelled assessment.
Can I ask whether as per the advice on thread-( new advice on when your assessment is cancelled.)
Should I put FAO the decision maker, on the letter or envelope?

Regards to all