The municipality around South Africa's capital, Pretoria, has been told to withdraw adverts suggesting the city's name had been changed to Tshwane.
The centre of the city will retain the name Pretoria
The decision follows a ruling by the Advertising Standards Authority, after a complaint from Pretoria residents.
The dispute is part of a row between the government, which wants African names adopted and some white groups.
The television advert had a voice saying: "City of Tshwane, Africa's leading capital city".
Pretoria was named after Andries Pretorius, a folk hero of the Afrikaner group, which set up apartheid.
Tshwane, which means "We are the same", is the name given to the area by early African groups.
Campaigners say the council continued with a 24m rand ($4m) campaign despite numerous requests to wait until the name's status had been finally settled.
It was "a reckless and fruitless wasting of taxpayers' money," said Freedom Front Plus spokesman Willie Spies.
They say the name change could end up costing the taxpayer and businesses in the city more than 1.5bn rand.
The victory for the residents association could be short-lived as South Africa's Geographic Name Changes Council is to meet later this year when it is likely to approve the change.
GNCC Chairperson T Ntsewa said: "The only issues we consider are whether the name change raises issues of duplication, or whether they are vulgar or offensive."
The council then makes a recommendation to the minister of arts and culture. The minister has always - so far - accepted their recommendations.