I’ve had to leave Australia suddenly due to a family member dying due to Covid-19 in my home country. I did not have time to organize a cancellation for my Mobile phone plan. Is there any other way apart from calling (I have tried from Indonesia and waiting time is long) where I can cancel? Can I send an email? Thank you!
You'd think email would be a cert these days but its not something Optus appear to monitor all that consistently. You should write your cancellation to:
Customer Relations Group, PO Box 306 Salisbury South 5106.
It should get processed in due course. Optus can also confirm when you stopped using the phone so you should put the date you had to leave Oz as the cancel date and mention it was because of the virus and you should (hopefully) get it backdated.