Optus customers have been left feeling vulnerable and outraged by the company’s poor communication a week after it announced a massive cyber-attack affecting millions of Australians.

Karen Walker says finding clear information about what happened – and what data has been stolen – has been incredibly difficult.

“There’s one email [from Optus], no advice on what we should do and we’re hearing more from the media than from Optus themselves,” Walker said.

“I’m very concerned. I haven’t seen anything within my emails or my bank accounts or anything that is suspicious, but that’s not to say that’s not going to come.”

On 22 September, Optus revealed a data breach in which the personal information of millions of customers was stolen, including names, email and postal addresses, phone numbers and dates of births.

Some customers also had identification numbers compromised, including passport, driver’s licence and Medicare numbers.

Optus has emailed some customers alerting them to the cyber-attack, including general information about what data might have been exposed. It encouraged customers to have a “heightened awareness” of suspicious activity and look out for contact from scammers.

Walker has been an Optus customer for 20 years but is now considering a different provider, saying she is “disgusted” by what occurred and how little direct communication and advice she has been offered.

Connie Quinn, also a 20-year Optus customer, has received a single email from the company. She tried to get in touch with Optus earlier in the week, waiting on a chat for three hours without a response.

“We need transparency which we’re not [getting], because apparently Medicare details have been compromised now too, which we weren’t notified about,” Quinn said.

“What else has been compromised that we don’t know about?”

Quinn is unable to take the time to get her licence number changed due to work commitments, saying the situation is “ridiculously” stressful.

“It’s just not good enough. They need to get in contact with everyone who’s been involved … because so many people haven’t had any communication,” she said.

“I’ve got one daughter who hasn’t had any communication at all [while] one daughter has.”

Optus’s online chat feature has been inundated since the hack was announced. People on social media have reported waiting three to four hours for a response, with some reporting waits of up to 18 hours.

But it isn’t just current customers struggling to find clear information about their stolen data. Tricia Smythe was an Optus customer 13 years ago and received an email five days after the hack to notify her that her information was compromised.

“I feel like they’ve failed their customers,” she said.

“Optus has mismanaged this situation greatly in the sense that they’re not providing the information they have at hand to the customers to put our worries at ease.”

The email sent to Smythe contained no specific details and even after calling Optus directly, she doesn’t know which of her ID points were taken.

“If you go the whole hog, you think it’s my Medicare card, my license, my passport, my name, my address – that’s everything. You feel so vulnerable, it’s like going into your office naked.”

Optus has offered those most affected a 12-month credit monitoring subscription through Equifax Protect, but customers have expressed frustration there has been no direct communication on how to access the service.