Chapman Store owner Amy Chapman said the central city work, which has closed parts of Dunedin’s main street to traffic, had "driven people away from town".
"The actual road workers have been so helpful; this is on the council.
"I accept there’s nothing we can do about it, but I would just like some support from the council."
The $60 million project for George St started in stages in late 2021 and was expected to be completed by April next year.
Ms Chapman said in the first few months of the year, before she moved across the road, her clothing business was down "more than 50%" on the same period last year, and she was "100% sure" this was due to ongoing roadworks.
"People are simply staying away from town, there’s nowhere to park, and it is unbelievably dead."
She said some businesses were struggling to pay rent and she believed the council could have done more to help businesses, including by offering rates relief.
A George St cafe owner, who declined to be named, reported a similar downturn.
"The situation is what it is, I appreciate the work needed to be done, but I don’t know what should be the way forward.
"There is a lot of stress in the industry. Many businesses are close to hitting the wall.
"The work needs to be finished. The road workers are working really hard, it’s not their fault. But it’s been brutal on businesses."
Other food outlets on George St confirmed business was "really bad" and it was a struggle to attract customers.
Council central city plan project director Dr Glen Hazelton said he knew the George St work was disruptive, and that some businesses were doing it tough at the moment.
"We’re working hard to complete this essential infrastructure and amenity project as quickly as possible."
The council was also doing everything it could to support local retailers, including marketing, the waiving of fees for outdoor dining areas and other promotions, he said.
"The project is delivering a much-needed upgrade of core infrastructure in the area, to avoid the infrastructure issues seen elsewhere and future-proof us against more severe weather events.
"It will also deliver a more people-friendly and vibrant environment above-ground once finished, which will also benefit businesses in the area."
Dr Hazelton said the work was "about six months" ahead of schedule.
"We understand this is a challenging time, with the increasing cost of living and pressure on household budgets, which also hurts retail and food and beverage businesses.
"This is why we have accelerated our construction programme to complete the work as quickly as possible."
From December 8, work would be dramatically scaled back with the reopening to traffic of St Andrew St, Hanover St and the Golden Block.