New South Wales has claimed success in reforms designed to stop real estate agents from underquoting as Victoria embarks on similar legal changes in an attempt to crack down on the practice.

NSW Fair Trading says complaints about underquoting have been in steady decline since the commencement of the reforms at the beginning of 2016.

The changes mean that agents can no longer give understated or vague property prices – for example, by using phrases like “offers above” – and if audited need to provide documentation to Fair Trading as to how they valued a property.

A Fair Trading spokesman told Guardian Australia that a compliance program check conducted in March identified 13 agents to be non-compliant with the new laws. But, overall, complaints from prospective buyers about underquoting had dropped, he said.

“In 2015, 236 complaints were received about underquoting,” he said. “In 2016 to date, 165 complaints have been received with a steady decline since February. The drop in complaints about underquoting since the new laws commenced, and the positive reaction to the underquoting law reforms from real estate agents, indicates that the new laws have been very successful.”

​Victoria ​introduced ​its legislation to ​crack down on underquoting on Thursday​. The laws will take effect from January.

Under the new laws, agents must provide prospective buyers with three recent comparable sales, an indicative selling price and the median price for the suburb. Advertising price ranges of more than 10% will be banned and, like in NSW, terms like “offers above” or “from” will be banned from pricing. Agents will also be audited.

Earlier this month, the real estate agency Hocking Stuart admitted to underquoting in the competitive property market of Richmond, located 3km from Melbourne’s CBD. Consumer Affairs Victoria told the federal court last week that the agency should face a severe fine. The agency is part of one of 13 investigations underway by Consumer Affairs Victoria.

But buyers’ agent and the chief executive of EPS Property Search, Patrick Bright, is not persuaded that the reforms are effective. He believes more can be done to increase transparency in the industry and to protect buyers from underquoting.

“All the government has done is fiddle around the edges with their reforms,” Bright said.

“Let’s just say an agent puts $1m as the price guide and then a buyer makes an offer of $1.1m, which the vendor then rejects. There’s no requirement for the agent to change the guide from $1m to $1.1m in the advertisements

“I’ve also had sales agents and vendors tell me they get around the legislation by saying to the vendor, ‘I know you want $1m but that price may scare off buyers. Would you mind if I put $900,000 on the paperwork to get interest, and then we will work buyers up from there?’.”

Bright has launched a petition on change.org calling for the NSW government to require that vendors and agents publish the reserve price of a property before the auction. A similar petition has also been launched in Victoria.

Bright believes the reserve should be made public at least seven days before auction.

“That still gives prospective buyers enough time to organise and pay for building and pest reports but allows them to drop out if they realise the property is beyond their price range,” he said.

“It is unfair to entice people to come to an auction and spend money, time and energy when the the truth is the reserve is set at a price where they were never even in the running.”

However, the Real Estate Institute of New South Wales president, John Cunningham, said he believes the reforms have made a positive difference and go far enough to protect prospective buyers.

He said prospective buyers sometimes wrongfully attributed being out of the running for a property to underquoting, when in fact it was just the market at play.

“It’s very easy to point the figure and say it’s underquoting,” he said.

“We recently had a property where we gave a guide of $800-850,000 but the market indicated that people would be willing to pay $850-900,000, so we revised the quote. It ended up going for $920,000. It can be an inexact science.”

Sydney’s property market was particularly difficult for vendors and agents to predict, he added, and said that, despite sales well over the reserve price being rare, those sales were the ones most often publicised giving buyers the impression of rampant underquoting.

“We have volatile market conditions; in Sydney we have the lowest supply I’ve seen in 40 years in the industry combined with the highest demand,” he said.

“The percentage of complaints is so minimal compared to the amount of properties sold. Ultimately people love the auction system, because it is one of the most transparent systems of buying there is.”

He disagreed that publishing the reserve price before the auction was reasonable. He believes that, too often, people think only of the problems faced by prospective buyers, rather than the rights of the vendor.

“Never in my career have I seen a vendor set reserve price any closer to an auction than two or three days before,” Cunningham said. “You just don’t know where to set the reserve until you gather all the feedback.”

Victoria’s minister for consumer affairs, Marlene Kairouz, said she was confident that Victoria’s reforms would lead to more transparency and set the right balance between the rights of the buyer and the vendor.

“Prospective buyers expect and are entitled to a level playing field,” she said. “This is about making sure they don’t waste time and money on properties they can’t afford. These laws send a strong message to agents: think twice before you underquote properties to our homebuyers.”