Businesses and residents in west London have held a protest against the congestion charge extension.
The protesters are planning further rallies
Up to 100 people attended the march in Kensington including local MP Malcolm Rifkind, according to organisers, West London Residents Association (WLRA).
The WLRA claimed 150 businesses in the Earls Court and Notting Hill areas have suffered a 25% downturn in trade since the scheme went live in February.
But transport chiefs said the charge has had no negative impact on business.
The WLRA said it has been conducting a detailed survey of the effect of the western extension on trade.
"About 150 businesses have so far taken part in the survey," said Gordon Taylor, the association chairman.
"Since the zone was extended there has been a drop in trade of between 15% to 50%, averaging at 25%."
He said the WLRA, which has been campaigning against the extension, is planning further marches in the next nine months.
"We don't want to lose the flavour of our local village high street," he said.
"If small businesses start moving away, all we will be left with is a homogenised high street with big brand chains."
Transport for London (TfL) said the extension has led to a reduction in traffic of around 10 to 15%.
A spokesman said TfL's own surveys have shown the charge "has had no overall negative effect on businesses within the zone".
"Four years ago, when the central congestion charge zone was introduced, there were claims that business in the area would be damaged but in fact 2006 saw central London outperform the rest of the UK in retail sales," he said.