Wheelchair-users said they are being forced to try to climb a flight of stairs at a disability benefits assessment centre in south London.
The centre on Cherry Orchard Road, Croydon, is on the first floor and wheelchair-users say they were told they were not allowed to use the lift.
Allan Prince from Croydon Disability Forum said it was "unacceptable".
Atos Healthcare said it warns customers in advance and offers appointments at another centre or a home visit.
The next closest disability assessment centre is 14 miles away in Balham, said disability campaigners.
Mr Prince, who has reduced mobility, said the centre in Croydon is on an incline and navigating the road up to the centre is a "struggle" for him and his wife Sharon who uses a wheelchair.
He said: "It was frustrating having to walk that far plus watch my wife struggle up these badly constructed drop kerbs before she even got to the doorway.
"It's totally unacceptable and I hope something is done very very soon to rectify the problems in these buildings."
Carol-Ann Peakin, chairwoman of Croydon Disability Forum, said: "Why on earth would you have an assessment centre in a building that excludes wheelchair-users or people with very poor mobility."
A spokeswoman from Atos Healthcare said the centre is approved by the Department for Work and Pensions.
She said: "The assessment centre is not on the ground floor and when making an appointment by telephone or post customers are advised that in the event of an emergency, when the lift would be out of use, they would need to be able to use the stairs.
"If they cannot, Atos Healthcare schedules an appointment at an alternative nearby assessment centre or a home visit is arranged."