It comes after the Te Aro franchise earlier drew the ire of renters' associations last August when it posted an ad on its Facebook page stating: "Your tenants may hate us. You will love us!"
Another ad at the time showed a photo of two people clinking glasses underneath a tagline that asked landlords if they were financing their tenants' social lives.
The ads were eventually pulled after Quinovic's head office intervened, saying they did not conform to the company's "brand standards".
Chapman said Te Aro's principal Alex Khera had assured the franchise its owners, staff, or contractors were not associated with the fake reviews.
"The Franchisor is taking this situation very seriously and has sought comment from the franchise concerned," he said.
"Quinovic Group office will continue to investigate the source of the reviews and has requested that all franchises ensure that reviews posted on Facebook and Google are legitimate."
Earlier this week, Real Estate Institute of NZ chief executive Bindi Norwell said "stories such as this" highlight why her lobby body had been calling for the regulation of property managers.
"If the property management industry was regulated, property managers would have a code of conduct that they must adhere to and behaviour such as these alleged fake Facebook reviews could have them potentially removed from the industry," she said.
She said the Fair Trading Act prohibited businesses engaging in "misleading or deceptive conduct", while the Advertising Standards Authority Code also required ads to be legal, decent and honest.
Norwell said the lack of regulations governing property managers meant there were no protections in place for customers, such as checks on money being held in a trust account and the establishment of a disputes resolution process or regulatory compliance standard.
"While there are many amazing property managers out there, their high standards are being undermined by others who don't have the same ethics," she said.
"If the Government really wants to help renters, it should regulate the property management industry."