Exclusive: It was a gut-wrenching one-two punch for New South Wales mum Kim Anesbury.

The first blow hit in 2019, after her son Ricky Court had died suddenly, and Optus rejected her desperate attempts to keep his mobile phone number for sentimental reasons.

The second landed last month, when she got two letters in quick succession from Australia's second-largest mobile provider, both addressed to her dead boy and within days of the third anniversary of his death.

READ MORE: The jobs that killed most Australians in 2021

According to the first Optus letter, a combination of Court's personal information had been exposed in Australia's biggest corporate cyberattack.

Inside the second envelope, and even more jarring, they confirmed the number of his NSW driver's licence was exposed, potentially taken by a hacker.

Anesbury was livid.

Three years earlier, she'd made it explicitly clear to Optus that her son was dead.

That was evident because Anesbury was asking that Optus let her keep paying for her son's account so she might have it transferred into her control.

At the request of Optus, she sent in his death certificate.

That was a sign, Anesbury thought, that things were going to fall in her favour.

But a few days later, Anesbury was left distraught after opening an email from Optus informing her "the number has been moved on".

Have you been affected by the Optus hack? Email ************@******om.au” target=”” >Details of almost 1000 Medibank employees also included in hack