Just a heads up fawema2001 as per the red advisory message on the right when you posted your question that we don't have access to or visibility of customer accounts here on our public forum.
From what you've described the late payment fee is for an overdue amount prior to the 4th of May. Customers don't receive them for paying one day late.
If you’re still needing a hand, we recommend messaging us via the My Optus App. The team is available 24/7 and are ready to assist customers as quickly as possible.
@Ray_YC I think this is about a potential future fee. Combining what I know and Ray said:
1) Optus are not issuing Late Fees at the moment (due to difficulties paying) - so you're probably safe.
2) Optus apparently don't issue late fees for being one day late - so you're probably safe
3) Optus are usually pretty good at re-crediting a one off late fee on request anyway - so you're probably safe
In summary, you're probably safe.
As you say @petergdownload we're just going with best guesses without having visibility of the account.
FYI the following Optus offers will be removed as of 1st of May