Figures seen by ITV Border show hundreds of people across Cumbria and southern Scotland still need help claiming Personal Independence Payment (PIP).
PIP was introduced in 2013 to replace the Disability Living Allowance, with the Government claiming it would cut the welfare bill and target those who need help the most.
At one branch of the Citizens Advice Bureau in Dumfries, staff helped 416 people with everything from paperwork to appeals in one year.
The charity says it's still the biggest issue people go to them for help with.
Staff are now calling for an end to repeat medical assessments.
Fundamentally the social security system is supposed to be a safety net, and it's not fulfilling that role anymore. One of the things we'd like to see change is the the repeat assessments.
Under the PIP system, people aged 16-64 can get between £22 and £141 a week depending how their condition affects them.
Once you apply, you're assessed by a healthcare professional. If you're refused or disagree with the amount of money you've been given, you can appeal.
The Department for Work and Pensions say the Personal Independence Payment system is fairer than the old Disability Living Allowance as payments match the claimants current needs.
Under PIP 28% of claimants are now receiving the highest rate of support, compared to 15% under DLA."
A survey of Citizens Advice advisors showed:
88% of frontline staff report seeing or being made aware of clients who have experienced inaccuracies on PIP assessment reports, with 67% reporting clients feeling rushed during their assessment.
75% report clients being asked to travel long distances to assessments.
62% report clients receive little notice of assessment dates and/or cancellation of dates.
There has been some progress with PIP, for instance waiting times for assessments have come down significantly, but our concern is there is still some way to go in terms quality and accuracy."
Watch Hannah McNulty's full report below: