Western Australia's state-owned power utility overcharged thousands of vulnerable customers over more than a decade, according to a new report.

WA's economic watchdog has been probing issues related to customers paying their power bills using Centrepay, which allows for automatic deductions from Centrelink support payments.



The Economic Regulation Authority (ERA) found in up to 2,845 cases, the utility had continued to take money from customers' Centrelink payments after they had closed their Synergy accounts.

It believes those issues date back to 2009 at a total cost of $2.29 million.



Changes to the code of conduct under which Synergy operates means it can only be ordered to repay 459 customers who were affected since February 2023 and are collectively owed $239,250.

But Synergy has indicated all customers will be reimbursed.



"This is a particularly concerning breach, given Synergy's position as the largest retailer in the state and the vulnerability of this cohort of customers that are receiving Centrelink support," ERA chair Steve Edwell said in a statement.

"We would expect Synergy to have systems in place that would have identified these payments accruing in closed accounts — with around 1,000 customers owed more than $500."

What is Synergy?​

Synergy is government-owned and WA’s largest electricity generator and gas retailer.

It provides 52 per cent of electricity to households and businesses in the South West Interconnected System.

The system covers Perth and extends from Kalbarri in the north, east to Kalgoorlie and south to Albany.

Source: Synergy website

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All customers will be paid: Synergy​

In a statement, recently appointed Synergy CEO Kurt Baker apologised to customers affected by the issue, saying "they were let down".

The ERA said the utility had been contacting affected customers since April, with around 30 per cent of the money owed paid back so far.



"Our systems are complex and identifying impacted customers took some time," Mr Baker said in a statement.

"As soon as possible after Centrepay overpayments were confirmed we took steps to resolve the issue and are continuing to do so."

The Synergy chief indicated all affected customers dating back to 2009 would be paid back, with about half of all refunds totalling $250 or less.





"We also expect Synergy to make changes to its customer management systems so that these sorts of payments are automatically flagged and dealt with," Mr Edwell said.

Mr Baker said a "thorough review" would be undertaken to make those changes.

"This review will identify any further overpayments on inactive accounts so that we can make refunds," he said.

Synergy has been ordered to make those changes and make "best endeavours" to repay all 459 customers by the end of November.

The ERA said while six other electricity and gas retailers in the state also charge customers via Centrepay, it did not believe the issue was widespread.

Opposition wants answers​

Shadow Energy Minister Steve Thomas said the revelation raised a range of questions for both Synergy and Energy Minister Amber-Jade Sanderson.

"Synergy knew about this breach in December last year and still did not immediately notify the 459 affected customers," he said in a statement.



"Did they notify the energy minister? Do they need greater resourcing to make sure this does not happen again?

"While I welcome Synergy's apology, there needs to be reassurances this cannot and will not happen again.



"Simply saying our systems are complex does not pass the pub test.

"This is just another example of the Cook government failing the most vulnerable members of our community."

In a statement, Energy Minister Amber-Jade Sanderson said customers using Centrepay should have confidence the system is working in their best interests.



"I have instigated an independent review of all systems and processes relating to customer billing in Synergy, to assess the customers affected and to ensure the integrity of the system going forward," she said.

"I will continue working closely with relevant agencies to ensure this issue is resolved and that appropriate safeguards are established."

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Written by: Keane Bourke, ABC News.