I had a contract with Optus for 5 years. It was perfect for my needs. 

I noticed some SMS and Emails from Optus about changing my contract but for two reasons I didn't pay much attention to them.

1. I don't click links on SMS and Emails anymore and after Optus data breach was kind of skeptical.

2. If it was a change the price was the same, they only mentioned adding extra data for use in Australia, which I don't use anyway. I did not think they would change the contract away from what I signed off on and I noticed that the same contract I have always had was in my profile in the Optus App.

Some time later noticed an extra 8 dollar charge on my account, then a couple of weeks later another $223 dollar charge.

The plan they put on did not include the normal 4GB roaming per month nor the roaming for calls. I live overseas for work so this is the only use of the service I need.

I called Optus and the customer agent was very unhelpful, offered no explaination, could not explain what my new contract allowed and could not explain why my old contract is still listed in my profile as our commercial agreement.

I still have no idea what the new plan includes it was never explained to me, I never signed anything or would never agree to remove the roaming as this is the only need I have for it. The calls were from my Mum and it cost $223 dollars.

OPTUS is acting illegally to migrate customers to new plans that are the same cost remove services then charge for them.

Abhorrent and appalling behaviour. 

My advice is avoid Optus at all costs unless you can be assured that once you sign up they will not simply transfer you to another plan that costs hundreds of dollars.