A disabled woman was left waiting at a bus stop after being told she could not board because prams were taking up too much space.
Eve Hogben, 28, who uses a wheelchair, was accompanied by her niece Amber, 21, when they were told they could not board the 71 bus at Copt Gilders in Chessington on Monday afternoon.
Wheelchair users are given priority over parents with pushchairs in the shared bay.
Dad Ian Hogben, 69, of Filby Road, Chessington, said: "The drivers don't insist that the people with pushchairs fold them up.
"One was prepared to get off the bus and wait for the next.
"Years ago the buggies always used to be folded.
"Now they're very reluctant to fold them up and drivers won't ask people.
"The wheelchair user doesn't have much alternative."
A London United spokesman said the incident was "regrettable and rare".
He added: "We endeavour to make disabled passengers' journeys as stress free and convenient as we can.
"Wheelchair users are given priority over parents with pushchairs in the shared bay.
"[While] one of the pushchair users offered to make room the other one refused, which would still not have been adequate for the procedure stipulated by Transport for London which we must adhere to.
"We would like to offer our apologies for the inconvenience caused."
Mr Hogben, a former bus driver, said he was "quite disgusted" by what happened, adding he thought London United was "passing the buck".
He added: "It's not the first time it's happened. It seems there's a regular thing.
"The same thing could equally happen if it's pouring with rain, or in winter, freezing cold.
"It's almost a case of discrimination against the disabled."
Fran O'Brien, founder of disability charity Yadapa and herself a wheelchair user, said: "I think the buses can be made a lot more accessible.
"It's a very difficult situation with the prams and I feel sorry for the mums. These days you could move house with one of those things - they're just enormous."
Motorised ramps allowing wheelchair access often break down, she added.