Hi AnonOrange
This tells you that you can put in for a Mandatory Reconsideration, challenging the decision. If you want to do this, having a copy of the assessment report is much easier, as you will then understand why they came to the decision they did. This is a PA4 if you had a telephone or face-to-face assessment. You can ring the DWP and request a copy of the report and it will take 7 to 10 days to reach you.
You can read about putting in for a Mandatory Reconsideration in the Guide to PIP Appeals, including the MR information.
benefitsandwork.co.uk/guides-for-claimants/pip BIS