I used the last of my data last night but left a good 50-100MB so I wouldn't go over as my data resets tomorrow. I get a message from Optus at 11:30 saying it's gone over. My data doesn't roll over so I need that removed off my bill ASAP or I'll just have to consider switching to Telstra. I mean I'm only here for the premier league. This seems to happen every month and I use the app so I don't need to pay an extra $10 but it always happens. The app and website are extremely unreliable and it seems your scamming me by taking money within the last couple of minutes of my last night. If this isn't fixed then I am switching
Data limits only need to be updated around 48 hours (Optus could go longer but that seems to be the ball park time). In practice Optus do tend to get data amounts within 15 minutes.
FWIW 75Mb isn't a huge amount and background phone syncing / apps / delayed data usage could easily tip you over IMO. Do you have a Windows or Android phone? You should set local data limits that you count. Not Optus.