Telstra

In 2018 the Federal Court fined Telstra $10 million for making false or misleading representations to customers in relation to its third-party billing service known as "Premium Direct Billing" (PDB), following action by the ACCC. The Court held, by consent, that Telstra misled customers and breached the ASIC Act when it charged them for digital content, such as games and ringtones, which they unknowingly purchased. Telstra admitted that more than 100,000 customers may have been affected and has committed to offer refunds to these customers.
Source: ACCC (2018)

In May 2021 Australia's Federal Court ordered that Telstra pay $50 million in penalties for engaging in unconscionable conduct when it sold mobile contracts to more than 100 Indigenous consumers across three states and territories, in proceedings brought by the ACCC. Telstra admitted that between January 2016 and August 2018, it breached the Australian Consumer Law and acted unconscionably when sales staff at five licensed Telstra-branded stores signed up 108 Indigenous consumers to multiple post-paid mobile contracts which they did not understand and could not afford.
Source: ACCC (2021)

In 2022 Telstra was ordered by the Federal Court to pay penalties totalling $15 million after admitting to making false or misleading representations to consumers when promoting certain NBN internet plans, in proceedings brought by the ACCC.
Source: ACCC (2022)

In 2022 Telstra refunded customers more than $1.73 million and paid a $506,160 infringement notice after it overcharged thousands of customers following investigations by the Australian Communications and Media Authority (ACMA). In 2020, the ACMA directed Telstra to comply with billing accuracy obligations after an investigation found it had overcharged more than 10,000 customers almost $2.5 million over a 12-year period. In 2023 a new ACMA investigation found Telstra issued inaccurate bills to more than 11,600 additional customers, including 4,400 who were given incorrect bills after the ACMA had issued Telstra the formal direction to comply with billing accuracy rules.
Source: ACMA (2022)