So my partner and I ended up switching ISPs on the 17/04/2020. Which was a great move, they picked up the phone within 20mins and resolved the above issue in the same amount of time. All on a Friday night!
The Monday after (20/04/20) I phoned to cancel our account with Optus. Through several departments I was then told that because there is an outstanding order on our account they could not cancel our service. The gent on the phone said that he would put a note on the order stating our intention to cancel and that was the best he could do. I asked if it was okay to cancel our direct debit in the mean time and he said that was okay.
We are still receiving bills from Optus 4 weeks later. I have been able to contact the accounts team via phone due to the offices opening time and my current commitments to work. When we use the app they only suggest that we call to cancel. How do I stop the bills?