However, ACCC acting chairman Mick Keogh said about 94,000 customers were yet to contact their providers about their slow NBN connections.
“A large proportion, two in three affected consumers, have not responded to the letter or email,” Mr Keogh said.
“They may be eligible for refunds, some in the hundreds of dollars.
“The ACCC is urging NBN customers to contact their NBN retailer if they have received a letter or email offer of a remedy, or think they might be entitled to a remedy.”
David Basell, an electronic engineer from Perth, said even though he signed up for top download and upload speeds with the NBN, they were not what he expected.
“The response wasn’t anywhere near what I would expect in terms of how the internet felt – I call it perkiness,” he said.
Mr Basell said that, compared with the two ADSL lines in one of his businesses, and his time spent living in the United States, the NBN was “quite variable” in speed.
He said his own monitoring of the download speed showed it varied from 90 megabits per second (Mbps) to 80, 70 and even as far down as 40 – a far cry from the 100 he signed up for.
“It went up and down like a yo-yo,” Mr Basell said.
Another problem he has with the NBN is the “asymmetrical speed profile” with slower uploading speeds – a particular problem, he said, as a business owner.
“Even when the download speed is solid as a rock at say 90 [Mbps], the upload speed is all over the shop,” Mr Basell said.
“I reckon the highest we’ve got out of it is 30 [Mbps], but most of the time it’s probably down around three, five possibly 10.”
Mr Keogh said retail service providers (RSPs) that advertised fast connection speeds they could not provide to customers risked breaching Australian Consumer Law.
“We expect RSPs to provide consumers with accurate information upfront about the internet speeds they can expect to experience, and then deliver on those promises.”
In a statement, a Telstra spokesman said the company “has implemented all commitments made to the ACCC and reported this information in line with progress”.
Service providers that agreed to enforceable undertakings also included iiNet, Internode, Dodo, iPrimus and Commander.
Optus and TPG have also been contacted for comment.
Rachel Clun is a journalist at The Sydney Morning Herald.