Mandantory reconsidration, How long does it take, and how's it done?

Hi @sanna - & welcome to the community. A Mandatory Reconsideration should be put in writing, either using this form: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/683380/if-you-disagree-with-a-decision-made-by-dwp.PDF   or by simply writing a letter, putting your name & National Insurance number on each page. If this is for PIP, remember this is not about any diagnosis, but rather how your disability affects certain activities of daily living &/mobility. Have a look at the activities/descriptors that are looked at with PIP: 

https://www.cambridgeshire.gov.uk/asset-library/Personal-Independence-Payment-Descriptors-and-Scores-April-2021.pdf

Try & give a couple of recent, detailed examples as to the difficulty you face for each applicable descriptor, i.e. when did it happen, where, what happened, did anyone see this, & were there any consequences to attempting/doing an activity?

Say if you can't do an activity 'reliably,' i.e. safely, to an acceptable standard, repeat as often as one would reasonably expect, or if it takes you much longer than someone without a disability. See this mentioned at the end of the link above.

Keep a copy of everything, & get a free Certificate of Posting from your Post Office when sending the form off. It can take anything from 2-12 weeks before a decision on this is made. Another decision maker will look at everything you've sent again.