The number of people in Wales seeking help to challenge the outcome of their Personal Independence Payments (PIP) assessment last year has nearly doubled.
The charity Citizens Advice Cymru says the number of people who have requested help with their appeals has risen by 86%.
PIP is a benefit that helps people to meet the extra costs of being disabled or having a long term health condition.
More than 3,800 people asked the charity for advice on how they might overturn their PIP assessment decision in the year ending March 2017.
That is up from 2,059 in the year to March 2016.
To receive PIP people must have an assessment to work out the level of assistance they need.
Citizens Advice Cymru says 'flaws' with the system can result in some people being wrongly assessed.
The charity says problems reported about PIP assessments include confusion over what evidence to submit in advance, being rushed for time during the assessment and the wrong information being recorded by assessors.
In some cases it’s possible to reverse a decision by asking for a reconsideration.
If this doesn’t work people’s next option is to appeal their case at tribunal.
PIP was the most common advice issue Citizens Advice Cymru helped with last year.
The Department for Work and Pensions says that only a 'small proportion' of decisions are overturned.