Some shops in Brecon have stopped paying business rates in protest at the closure of a street, which they claim is crippling trade.
Only buses and taxis can exit the Bulwark in Brecon
Firms in an area known as the Bulwark, said a fall in passing trade had seen sales drop by 50% in some cases.
As part of a new relief road opened in June, Powys Council shut the end of the Bulwark except for buses and taxis.
The council said the move reduced traffic and improved safety for shoppers.
But shopkeepers said the closure of the Bulwark confused visitors and diverted them away from their shops.
Former police officer Ian Dent and his wife Claire own A-Frame Gallery.
Father-of-two Mr Dent said: "We opened in December last year and in one month we took £14,000, but since the relief road opened our sales have dropped by 50%.
"We've decided to stop paying our business rates in protest until we get some answers and the council agrees to meet with businesses. We're paying the rates into a trust fund at the moment."
Deb Keener jointly runs The Ink Well, a craft and gift shop in the nearby Watton area. She said town centre trade was being "crippled".
"If things don't improve my business partner and I will be forced to relocate," she said.
"I'm not opposed to the relief road, it's just that all traffic is being forced to use it to the detriment of the Bulwark in the town centre."
Michael and Carol Mulley of the Lansdowne Hotel, also in the Watton, have noticed a drop in passing trade.
Mr Mulley said: "It is the leanest period we've experienced since foot-and-mouth.
"Thanks to the closure of the Bulwark, we now have to guide guests to the hotel by phone, even ones who've been here before."
Jeweller Hazel Hillman, in the Bulwark, has been in business for 25 years and said she intended to stop paying her business rates next month.
"The Bulwark has become a glorified bus stop and taxi rank," she said.
"Since the road closed my turnover is down 60%."
A Powys Council spokesman said: "The £3.5m inner relief road aims to provide long-term benefits to Brecon town centre, reducing traffic in the centre, improve pedestrian safety and provide a public transport interchange.
"Further maintenance and refurbishment works are planned for the town centre to further enhance the street scene and improve pedestrian facilities."