The council was asked to investigate the "urgent" problem in 2006
Traders in London's famous Portobello Road market will be refunded £728,000 by their council after it overcharged them for waste disposal for 18 years.
Kensington and Chelsea borough council admitted charging market traders for disposing of waste that was not theirs.
Trader Maureen Peck said: "We have been complaining about this for years."
Councillor Nicholas Paget-Brown said: "An error was made and we have put it right." Traders would receive their refunds "very soon", the council added.
Mr Paget-Brown said waste from the dozens of street traders in the road is disposed of at the same time as shopkeepers' waste and some household waste.
"What happened was that the complexity of this meant that the traders were being overcharged," he said.
Ms Peck said: "They have been collecting everybody's rubbish along the Portobello Road - all the coffee shops and cafe bars and other buildings.
"Then it all gets put onto our truck, it's weighed and that is put onto our bill."
Mr Paget-Brown told BBC London that the council began to investigate the problem "as a matter of urgency" two years ago, after complaints from traders.
"We have looked into it, it's been immensely complicated, and we have now decided that a rebate for the cost of waste disposal is in order," he said.
"We are going to make sure each of the traders trading over the last six years gets an individual refund depending on how long they have been trading in the street."
Ms Peck, who has been trading in Portobello Road for 15 years, denied the money was a "windfall".
She said: "It's our own money coming back and, not to sound greedy, most probably not all of it."