Hi Mattm682!
Welcome to AGL Community!
That sounds very stressful! High bills can be a cause for concern, but the good news is there is a few checks you can do first.
First thing I would check was that your bill before this one was an actual reading, not an estimation. With the lock down in Victoria, it is possible that the bill prior to this had to be an estimation, which would cause any unbilled usage to be applied to this bill.
If that's not the case, then I would recommend running an isolation test. You can do this by check the meter reading, waiting a few hours with NO usage, then check it again. If the meter readings don't change, then your meter likely isn't faulty.
You can learn more about high winter gas bills on a similar post here: Extremely High Gas Bill
If you are having issues with this, or would like some further support please feel free to reach out to our dedicated team on the AGL App or My Account for further investigations.
Thank you
Ellen