You can ask for a mandatory reconsideration over the phone, but you should confirm your request in writing. Write to the office address on the decision letter and keep a copy of your request. You can also ask for a mandatory reconsideration using form CRMR1
When you ask for a mandatory reconsideration, you should explain why you think the decision is wrong. If you can, get evidence to back up your argument.
In the case of benefits paid because of your disability or health condition, such as personal independence payment (PIP) or employment and support allowance, you will need to see the evidence that was used in making the decision before you can properly argue your case. In this case, write to the address (or ring the number) on the decision letter and do the following:
Request a mandatory reconsideration of the decision. State your grounds simply at this stage, such as (for PIP), ‘I believe that you have underestimated the degree of my disability and consequently underestimated the extent of my mobility problems and/or the difficulties I have in carrying out daily living activities’;
Ask them to send you copies of all the evidence that was used in making the decision; and
Ask them not to take any further action until you have had the chance of responding to that evidence.
When you do receive the evidence, you should have a better idea of why the decision was made. This will help you frame your argument and build up evidence to support your case.
Resources
The Disabled People's Manifesto
DPO Forum England The collective voice of Deaf and Disabled People's Organisations in England
Working with Disabled People’s Organisations, public bodies, businesses and Government across the UK to influence regional and national change for better rights, accessibility, benefits, quality of life and economic opportunities for Disabled people.