One of the companies, Internet Name Protection, is also reportedly charging customers $220 for the same renewal service that domain name registrar Melbourne IT charges $137.50 for.
A group of ISPs have already blocked customer access to the website of Melbourne-based company Domain Name Authority of Australia (DNA) after the organisation was found to be sending "misleading" letters.
DNA is approaching domain-name holders whose subscription is up for renewal and offering re-registration services. The names of the holders are being sourced from a publicly available database, DNA said.
According to Jason Briers, a systems engineer from Townsville ISP Beyond Net, which is leading the blocking action, the ISPs are also considering including Internet Name Protection in the block.
A third unnamed company is believed to be conducting similar behaviour, Briers added.
Craig Waldon, director of golf wholesaler Surrey Golf, who renewed his domain name after receiving a letter from Internet Name Protection, said that in addition to sending the unsolicited letter, Internet Name Protection claims it is legally entitled to approach domain-name holders and that its service is faster than Melbourne IT's.
Waldon said the letter from Internet Name Protection started with "As a channel partner of Melbourne IT . . ." and led him to believe the company was associated with or was the same company he originally registered with. He registered his domain name with Melbourne IT in 1998.
The letter also implied that he should renew his domain name as soon as possible or risk losing it. "The language in the letter is quite aggressive," Waldon said, adding that Internet Name Protection "used all the standard scare tactics".
He said he was only alerted to "the scam" after receiving another renewal notice from Internet Names Worldwide, the division of Melbourne IT now responsible for renewal services, advising of the $137.50 renewal fee and after he had sent Internet Name Protection a $220 payment.
In a letter to the Department of Fair Trading on the matter, Waldon said: "I am of the belief that the letter from Internet Name Protection misrepresents who we are paying the renewal fee to and the wording is very firm in suggesting that [we] need to renew our name with them."
Waldon said that Melbourne IT is aware of Internet Name Protection's actions, but is "not getting anywhere in stopping them".
Meanwhile, Adam Todd, founder of the Australian Root Server Confederation and an advisor to ISPs, is recommending Melbourne IT drops DNA from its channel partner program. If Melbourne IT continues to allow such practices to be undertaken by DNA the organisation could also face legal action, he warned.
Todd is looking for more ISPs and consumers who say they have been misled by DNA to take part in legal action against Melbourne IT and DNA.