Two major telecommunications companies will refund nearly 40,000 customers after charging them for internet speeds that weren't being delivered.
Optus and TPG have refunded their customers more than $4.4 million and $2.1 million respectively.
Both companies failed to alert customers the speeds advertised in their internet plans could not be met on the NBN infrastructure available.
The telcos self-reported their errors to the communications watchdog in 2021.
Under the watchdog's rules, telcos must verify maximum internet speeds when swapping customers to the NBN and let them know if the speeds cannot meet what was originally advertised.
Around 34,000 Optus customers over a two year period did not receive the level of service they had purchased and 4400 TPG customers were affected by the same issue.
Australian Communications and Media Authority chair Nerida O'Loughlin says telcos must be more vigilant to deliver on their advertised promises.
"Optus and TPG were charging these people for internet speeds they could not get," she said.
"These customers were left in the dark and denied the option to move to a cheaper contract or walk away."
Optus and TPG must now conduct independent audits into their compliance systems.
The watchdog required Telstra to conduct an audit in 2021 for similar issues.
